.H3 



ALLOYS OF CHROMIUM, 
COPPER AND NICKEL 



BY 



OSCAR EDWARD HARDER 

B. A. University of Oklahoma, 1910 
M. A. University of Oklahoma, 1911 



Thesis submitted in partial fulfillment of the requirements for 

the degree of Doctor of Philosophy in Chemistry in 

the Graduate School of the University of Illinois, 

1915 



ALLOYS OF CHROMIUM, 
COPPER AND NICKEL 



BY 



OSCAR EDWARD HARIDER 
B. A. University of Oklahoma, 1910 
M. A. University of Oklahoma, 1911 



Thesis submitted in partial fulfillment of the requirements for 

the degree of Doctor of Philosophy in Chemistry in 

the Graduate School of the University of Illinois, 

1915 



>i^lUC--0./vx><Xj\<^\T^ 



.H3 







out 

TtaColTsr:.!* 

JUL 2 m 



|7-;^^lo\ 



CONTENTS 



CONTENTS 

I. Introduction • page 

1. Purpose of the Investigation 5 

2. Present state of information 5 

3. Plan of Work 6 

4. Summary of Results and Conclusions 6 

II. Preparation of the Alloys 

5. Materials 8 

6. Melting the Metals 9 

7. Casting the Samples 10 

8. Composition of the Alloys 10 

9- Analysis 10 

10. Changes in Composition 10 

11. Alloy of 50 Per Cent Cr. and 50 Per Cent Cu 12 

III- Physical and Mechanical Properties 

12. Color and Appearance 14 

13. Method of Plotting Diagrams 14 

14. Specific Gravity 14 

15. Brinell Hardness Number _ 17 

16. Tensile Strength and Stress Deformation Tests - 18 

Test Pieces .^. 18 

Testing Machine and Method of Loading 18 

\ Extensometer 18 

Calculation of Modulus of Elasticity 18 

Reduction and Elongation 19 

Ultimate Strength 20 

Modulus of Elasticity 20 

IV. Corrosion Tests ' page 

17. Reason for Tests 20 

18. Materials 20 

19. Methods 22 

Solutions -J 22 

Suspending the specimens - 22 

Temperature 22 

Time 22 

Calculations -. - -— 22 

Accuracy of the Method '2?, 

20. Results - 23 

Nitric Acid 24 

Hydrochloric Acid — 26 

Sulfuric Acid '2^ 

Sodium Hydroxide -..- — 26 

Ammonium Hvdroxide - --— 27 

Sodium Chloride - 27 

Fatty Acids • • 27 

Comparison of Corrosions 28 

21. Conclusions 28 

V. Relation Between Corrosion and Pflative Electromotive Forces 

22. Purpose of Measurements 29 

23. IMethod and Results of IMeasurements 30 



4 CONTENTS 

VT- Thermal Analysis and Microscopic Examination 

24. Difficulties of Thermal Analysis". 33 

25. Heat Treatment 35 

26. Microscopic Examination '. 35 

General Discussion , • 35 

Etching Reagents .v. .'—. •. 36 

Ferric Chloride and Hydrochloric Acid 36 

Iodine 36 

Results 

Chromium-N'ickel Alloys 36 

Copper-Nickel Alloys 37 

Solubility of Chromium in Copper t,7 

Effect of Nickel on the Solubility of Chromiuin 37 

Crystals in Nickel-rich Alloys 38 

Annealing Tests 38 

Appendix. — Historical Review 

1. Copper-Nickel Alloys — , , 52 

2. Chromium-Copper Alloys 54 

^. ChrOrnium-Nickel Alloys .....j 54 

4. Ternary Alloys : 57 



LIST OF FIGURES pace 

Diagrams Showing Alloys Having Possible Commercial Value 9 

and 3- Microphotographs Showing Separation of Copper from Chromium 

in a 50 Per Cent Cu., 50 Per Cent Cr. Alloy 13 

Diagram Showing Composition of Alloys and Specihc Gravities at 25 C... 15 

Stress Deformation Curves for Alloys ; 21 

Diagram Showing Composition of Alloys and Corrosion in Normal Nitric 

Acid Solution 33 

Diagram Showing Composition of Alloys and Corrosion in Normal Hy- 
drochloric Acid Solution 24 

Diagram Showing Composition of Alloys and Corrosion in Normal Sul- 
furic Acid Solution ,. , 26 

Diagram Showing Composition of Alloys and Corrosion in Normal So- 
dium Hydroxide Solution ;... 27 

DiagTam Showing Composition of Alloys and Corrosion in Normal .■Xm- 

monium Hydroxide Solution 28 

Diagram Showing Comnosition of Alloys and Corrosion in Normal So- 
dium Chloride Solution 20 

Diagram Showing Composition of Allovs and Corr'^s'on in Fattv Acids 30 
Diagram Showing Comoosition of Allovs and their C1''^'''Qps in Fle'^tr'^- 

motive Force in a Four Normal Sodium Chloride Solution 33 

Id to 6.S. Micronhotographs of the Alloys 30-=;i 

66. Copper-Nickel Equilibrium Diae^ram After Tafe1 "^ 

6*7. Copner-Chromium Equilibrium Diagram After Hindrichs S" 

68. Nickel-Chromium Equilibrium Diagram After Voss 56 

LIST OF TABLES 

T. Composition of Allovs it 

2- Hardness, Specific Gravity and Kind of Castings i6 

3. Hardness Test bv Canada Department of Mines 17 

4. Comnosition, Modulus of Elasticity, and Ultimate Tensile Strength of 

Alloys TQ 

1^. Corrosion in Normal Nitric Acid 2.; 

6. Comparison of the Corrosions in the Different Solutions 31 

7. Relative Electromotive Forces of the Different .Mloys in Contact with 

Four Normal Salt Solutions 3-^ 



10 

TI 

T2 
13 



A PRELIMINARY STUDY OF THE ALLOYS OF CHROMIUM, 

COPPER, AND NICKEL* 

I. Introduction 

1. Purpose of tJie Investigation. — The growing interest in special 
acid-resisting alloys and the many uses found for them has stimulated 
both the search for efficient materials of this nature and the study of 
the causes underlying their inertness. The alloys developed by 
Professor S. W. Parr for use in calorimeter construction have shown 
this quality of high resistance to corrosion to a marked degree. The 
almost perfect insolubility of these alloys in nitric and other acids 
seems to be conditioned upon a proper mixture of chromium, copper, 
and nickel, together with smaller quantities of such added metals as 
tungsten or molybdenum.! 

These additions have so marked an effect in improving both the 
acid resisting properties and the casting qualities of the alloys that it 
has seemed desirable to study their effects more systematically in 
order that they may be used to the best advantage. The complexity of 
the mixtures used, however, has made the problem a very difficult one 
and has shown the necessity of first obtaining a more complete knowl- 
edge of the ternary alloys of chromium, copper, and nickel, and of the 
binary alloys of copper and nickel, copper and chromium, and 
chromium and nickel. With this information in hand it should be 
possible to understand better the effects produced by additions of 
a fourth metal. 

In the work presented in this bulletin a preliminary survey has 
been made of the binary and ternary alloys and a somewhat systematic 
study made of their properties. 

2. Present State of Information. — Previous investigators have 
studied in some detail the equilibrium conditions in the three binarj* 
systems. The freezing point curves for copper-nickel and chromium- 
nickel alloys have been fairly well established, but that for the chro- 
mium-copper series has been determined only in part, owing to the 
unusual difficulties attending the work. According to available in- 
formation, these alloys belong to three different classes ; copper-nickel 



*The manuscript for this bulletin was originally pi-epared by Mr. Oscar E. Harder and 
submitted by him in partial fulfillment of the requirements for the degree of Doctor of 
Philosophy, University of Illinois. Since its presentation as a thesis, it has been reviewed 
and in certain particulars revised by Dr. D. F. McFarland. 

tS. W. Parr, Orig. Com. 8th Inter. Congr. Appl. Chem. Vol. 2, p. 209, 1912. Also 
Jour. Am. Chem. Soc. Vol. 37, pp. 2515-2522, 1915. 



6 ILLINOIS ENGINEERING EXPERIMENT STATION 

forming a continuous series of solid solutions (or mixed crystals), 
chromium-nickel consisting of solid solutions with a minimum point 
which is said to be a eutectic point, and chromium-copper having two 
eutectic points with a wide range in which the metals do not alloy. 

The alloys of copper and nickel are commercially important in 
the form of Monel metal (Cu 30 per cent, Ni 70 per cent), Constantan 
(Cu 60 per cent, Ni 40 per cent) and other resistance alloys, and 
nickel coin (Cu 75 per cent, Ni 25 per cent). Chromium-nickel alloys 
such as "Nichrome" and similar resistance alloys have important 
uses. Chromium-copper alloys of a limited range of composition are 
also obtainable on the market. The solubility of chromium in copper 
has been placed at from 0.5 to 10.0 per cent by various investigators, 
while the solubility of copper in chromium has been placed at less 
than 5.0 per cent. 

3. Plan of Work. — It was originally intended that this investiga- 
tion should include the following: 

a. The preparation of samples of both the binary and ternary 
alloys which would represent all of the possible combinations with 
variations of 10 per cent of the different constituents. 

b. Physical and mechanical examinations which would include 
color, appearance, specific gravity, hardness, tensile strength, reduc- 
tion of area, elongation, and modulus of elasticity. 

c. Corrosion tests in solutions of nitric acid, hydrochloric acid, 
sulfuric acid, sodium hydroxide, ammonium hydroxide, and sodium 
chloride, and in fatty acids. 

d. Measurements of the relative electromotive forces of the alloys 
in contact with salt solutions. 

e. Thermal analysis and heat treatment. 
/. Microscopic examination. 

This program has been carried out with the exception of the 
thermal analysis and heat treatment. Considerable time and effort 
have been expended on the attempt to work out the former, but the 
experimental difficulties have been so great that it has been necessary 
to reserve this analysis for further work and future report. It was 
thought best also to postpone the study of heat treatment until the 
equilibrium diagram could be obtained. 

4. Summary of Results and Conclusions. — The results obtained 
together with the conclusions drawn from them may be summarized 
as follows: 

a. Methods have been developed for making castings of alloys of 
chromium, copper, and nickel ; and twenty-one binary and thirty ter- 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 7 

nary alloys have been prepared. From this part of the work the 
following conditions have been drawn. 

(1) Castings of chromium and copper containing as much as 
13 per cent of chromium can be prepared by melting and pouring the 
metals at about 1600 degrees C. 

(2) Chromium-copper alloys containing 6.08 per cent or 
more of chromium show a separation of chromium or of a chromium- 
rich constituent, if they are cooled slowly. 

(3) If equal weights of chromium and copper are heated 
together to a temperature well above the melting point of chromium 
and slowly cooled, the alloy is not homogeneous, but consists of two 
layers ; the lower rich in copper, and the upper rich in chromium. 

(4) The addition of nickel to alloys of chromium and copper 
tends to prevent the separation of the chromium or chromium-rich 
constituent; when the amount of nickel is more than three times the 
amount of copper present, the alloys become practically homogeneous. 

b. Physical and mechanical tests have been made with the fol- 
lowing results : 

(1) The specific gravity at 25 degrees C. of the alloys tested 
varies from 8.92 to 7.89 and decreases with an increase of chromium. 

(2) The Brinell hardness number varies from that of pure 
copper to that of tool steel and increases with an increase of chromium. 

(3) The modulus of elasticity of the sixteen alloys tested 
varies from less than 15,000,000 to more than 40,000,000 pounds per 
square inch. Generally it increases with an increase of chromium. 

(4) The ultimate tensile strength of the eighteen alloys tested 
varies from less than 10,000 to more than 50,000 pounds per square 
inch. 

(5) The reductions and elongations are small in all cases. 

(6) The stress-deformation curves are similar to those of cast 
iron. 

c. More than three hundred corrosion tests have been made. 
Results show that: 

(1) The amount of corrosion is not proportional to the 
strength of the acid or base. 

(2) A triangular system of plotting shows certain fairly 
well-defined areas which are highly resistant to corrosion. 

(3) Not only the alloys in the region approximating the 
composition of the alloy developed by Professor Parr are highly non- 
corrodible, but others have shown equally good resistance to corrosion. 
In general the ternary alloys are less corroded than the binary, though 
there are some exceptions. 



8 ILLINOIS ENGINEERING EXPERIMENT STATION 

d. An atthnpt has been made to find some relation between the 
relative electromotive forces obtained by placing the alloys in contact 
with 4 Normal sodium chloride solution and their relative resistance 
to corrosion, but no such relation has been found from the experi- 
mental data obtained. 

e. A microscopic study of the alloys has been made and the fol- 
lowing agreements with earlier iuA^estigators have been found: 

( 1 ) The results agree with Voss ' conclusions that chromium 
and nickel form a series of solid solutions (mixed crystals) over the 
range of 100 to 50 per cent of nickel and that they form a eutectic, or, 
as Guertler called it, a pseudoeutectic, containing about 42 per cent of 
nickel. 

(2) The results on the copper nickel series agree with those 
of Guertler and Tammann in showing a continuous series of solid 
solutions. 

(3) All nickel-rich alloys, both binary and ternary, show 
well-defined polyhedral crystals. 

/. In general the results indicate that the alloj^s of chromium- 
copper-nickel which show possibilities of becoming of commercial im- 
portance are limited to certain rather well-defined ranges of composi- 
tion. In Fig. 1 is shown diagrammatically what seems to be the most 
promising field for future investigation. In the nickel-rich corner 
of the diagram the alloys have very large polyhedral crystals and a 
coarse texture, and have usually developed blow-holes in casting. There 
is a possibility that the texture can be improved by the addition of a 
fourth metal as Professor Parr has done by the use of tungsten or 
molybdenum. The alloys containing large percentages of chromium 
have such high melting points and are so hard to prepare that, unless 
they find special and important applications, there is little chance of 
their being used commercially. Alloys containing large percentages of 
copper with chromium show such a marked segregation that they do 
not machine well and their mechanical properties are poor. The re- 
gion which promises best from the mechanical and physical standpoint 
is also, as a general rule, highly resistant to corrosion in the various 
solutions tested. 

II. Preparation of the Alloys. 

5. Materials. — All the materials used in the preparation of the 
different alloys were of good quality. The chromium was secured from 
the Goldschmidt Thermit Company and was labeled 98.99 per cent 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 



9 



chromium. An analysis of one sample showed 98.2 per cent chromium 
with the remainder consisting largely of silica, slag, etc. The nickel 
was C. A. F. Kahlbaum's "Nickel in Wurfeln" and an analysis 
showed that it contained 99.6 per cent of nickel, a small amount of 
iron, and only a trace of cobalt. Tw^o different lots of copper were 
used, both of which were electrolytic; one purchased from the J. T. 
Baker Chemical Company and the other from Kahlbaum. 




Fig. 1. Diagram Showing Alloys Having Possible Commercial Values. 



6. Melting tJie Metals. — The samples, with the exception of No. 
1 to No. 6, inclusive, were melted in Crescent Safety crucibles in a 
Hoskins electric furnace of the carbon plate resistor type. These 
crucibles are sand crucibles covered with graphite. They withstood 
temperatures as high as 1600 degrees C, and in only one or two cases 
did they seem to be softened by that heat. It was not possible to use 
a crucible for more than one melt because of the corrosion of the sand 
lining. Samples No. 1 to No. 6, inclusive, were melted in a gas-fired 



10 ILLINOIS ENGINEERING EXPERIMENT STATION 

furnace in fire-clay crucibles. The metals were protected by a cover 
of powdered cryolite (NaAlF4) which melted easily below the melting 
point of copper and effectively prevented oxidation of the chromium. 
It was not volatilized at the temperatures used and was the most 
satisfactory cover, although a number of other covers and fluxes 
were tried. 

The charges of metals were of uniform size, 300 grams, in all 
cases. The furnace used from 25 to 30 kw. per hour and the time 
required for a melt varied from two to three hours. 

7. Casting tJie Samples. — The molten metals were poured into 
asbestos-lined iron moulds % inches in diameter and about 8 inches 
in length, which had been heated to a bright red temperature and 
packed in amorphous silica. By taking a reasonable amount of care 
it was possible to prevent contact of the molten alloy with the iron 
mould and to insure its easy removal from the mould when cold. The 
silica, being a good non-conductor of heat, allowed the casting to cool 
very slowly. 

8. Composition of Alloys. — The intended composition of the dif- 
ferent alloys is given in Table 1. The percentages are expressed in 
both atomic per cent and weight per cent. The weight per cent was 
calculated from the atomic per cent by means of the following formula 
in which A, B, and C represent respectively the three metals chro- 
mium, copper, and nickel. 

„, . ^ ^ At. % ^x at. wt.^xlOO 

W ei srht per cent A =- — ——=^ =: — 7- 

^ At. % ^x at. wt.^ H-at. % ^xat. wt. 5 ^ at. % Cxat. wt. 6. 

In these calculations the values Cr = 52.00, Cu = 63.57, and Ni = 
58.68 were used as the atomic weights. Table 1 shows also the Aveight 
per cent composition of the castings found by analysis. 

9. Analysis. — Three methods of sampling were used. For some 
of the softer alloys the sample was obtained by making drillings ; for 
the specimens which were turned to test pieces the turnings were used 
for analysis; in all other cases a piece was taken from one end of 
the specimen. The copper and nickel were determined electrolytic- 
ally.* Chromium was determined by precipitating it as the hydroxide, 
and by igniting and weighing it as the oxide. In a few cases one of 
the constituents was determined by difference as indicated in Table 1. 

10. Changes in Composition. — A comparison of the composition 
of the charge with the composition of the casting, as found by analysis, 



*The preparation of the samples for analysis and the electrolytic determination of copper 
and nickel in all of the alloys were done by Sydney M. Hull. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 11 



Table 1 
Composition of Alloys 



Atomic Per Cent 
Composition 



Cu 



Cr 



Ni 



Weight Per Cent 
Composition 



Cu 



Cr 



Ni 



Weight Per Cent 
Composition by Analysis 



Cu 



Cr 



Ni 



1 


100 






100. 












2 


90 




10 


90.71 




9.29 


90.84 






9.06 


3 


80 




20 


81.27 








18.73 


81.07 






18.76 


4 


70 




30 


71.65 








28.35 


71.16 






28.46 


5 


60 




40 


61.90 








38.10 


61.63 






38.25 


6 


50 


* * 


50 


52.00 








48.00 


48.96 






49.90 


7 


40 




60 


41.94 








58.06 


69.13 






30.59 


8 


30 




70 


31.70 








68.30 


41.14 






58.27 


9 


20 




80 


21.31 








78.69 


20.65 






79.35t 


10 


10 




90 


10.74 








89.26 


10.57 






88.90 


11 


. • . 




100 


. . . 








100.00 


00.00 






99.66 


12 


90 


16 


. . . 


91.68 


9.32 




94.20 


6.08 


00.00 


13 


80 


10 


10 


82.12 


8.40 


9.48 


84.36 


7.79 


9.28 


14 


70 


10 


20 


72.43 


8.45 


19.12 


74.63 


8.25 


16.05 


15 


60 


10 


30 


62.58 


8.53 


28.89 


66.32 


10.63 


22.94 


16 


50 


10 


40 


52.57 


8.60 


38.83 


54.71 


15.94 


29.35 


17 


40 


10 


50 


42.40 


8.67 


48.93 


42.56 


10.13 


48.00 


18 


30 


10 


60 


32.05 


8.75 


59.20 


32.69 


13.97 


54.16 


19 


20 


10 


70 


21.55 


8.81 


69.64 


20.85 


11.80 


66.25 


20 


10 


10 


80 


10.87 


8.89 


80.24 


11.83 


11.90 


76.27t 


21 


. . . 


10 


90 




8.96 


91.04 


00.00 


19.37 


78.99 


22 


80 


20 


. . . 


83.02 


16.98 


« • • 


87.93 


13.15 


00.00 


23 


70 


20 


10 


73.22 


17.12 


9.66 


80.58 


10.56 


9.38 


24 


60 


20 


20 


63.28 


17.25 


19.47 


56.30 


14.56 


29.24 


25 


50 


20 


30 


53.16 


17.40 


29.44 


66.92 


13.62 


19.20 


26 


40 


20 


40 


42.88 


17.54 


39.58 


44.08 


19.30 


36.34 


27 


30 


20 


50 


32.41 


17.69 


49.90 


36.70 


15.99 


47.311 


28 


20 


20 


60 


21.80 


17.83 


60.37 


22.20 


19.86 


57.36 


29 


10 


20 


70 


10.99 


17.98 


71.03 


10.88 


19.64 


68.62 


30 




20 


80 




18.14 


81.86 


00.00 


21.52 


76.95 


31 


70 


30 




74.05 


25.95 




89.82 


9.89 


00.00 


32 


60 


30 


16 


63.99 


26.17 


9.84 


73.63 


17.66 


8.55 


33 


50 


30 


20 


53.77 


26.38 


19.85 


59.62 


22.00 


19.48 


34 


40 


30 


30 


43.37 


26.61 


30.02 


45.70 


25.10 


29.52 


35 


30 


30 


40 


32.79 


26.84 


40.37 


33.76 


29.46 


36.78t 


36 


20 


30 


50 


22.05 


27.06 


50.89 


22.58 


28.10 


48.42 


37 


10 


30 


60 


11.12 


27.29 


61.59 


10.90 


29.70 


58.12 


38 




30 


70 




27.52 


72.48 


00.00 


28.44 


71.56t 


39 


' 60 


40 


. . . 


64.71 


35.29 




Not analyze 


;d 


40 


50 


40 


10 


54.38 


35.58 


10.04 


70.57 


19.93 


8.99 


41 


40 


40 


20 


43.86 


35.89 


20.25 


54.16 


31.63 


t 14.21 


42 


30 


40 


30 


33.17 


36.20 


30.63 


33.60 


38.16 


26.78 


43 


20 


40 


40 


22.31 


36.50 


41.19 


22.68 


41.32 


34.60 


44 


10 


40 


50 


11.25 


36.82 


51.93 


11.02 


43.30 


46.46 


45 




40 


60 




37.14 


62.86 


00.00 


44.93 


56.55 


46 


'56 


50 


. . . 


55.20 


44.80 




Not prepared 




47 


40 


50 


10 


44.38 


45.37 


10.25 


Not prepared 




48 


30 


50 


20 


33.57 


45.76 


20.67 


28.42 


54.92 


17.12 


49 


20 


50 


30 


22.58 


46.16 


31.26 


24.12 


47.54 


26.28 


50 


10 


50 


40 


11.39 


46.56 


42.05 








51 




50 


50 




46.96 


53.04 


ob.bd 


57.40 


41.66 


52 


40 


60 


. . . 


44.89 


55.11 




. 


. 




53 


30 


60 


10 


33.96 


55.59 


10.45 


. . . 


. . . 


. 


54 


20 


60 


20 


22.85 


56.06 


21.09 


. . . 




. . . 


55 


10 


60 


30 


11.53 


56.56 


31.91 


Not analy 


zed 


56 




60 


40 




57.07 


42.93 


Not analy 


zed 


57 


30 


70 




34.37 


65.63 




• • • 






58 


20 


70 


' id 


23.13 


66.21 


11.56 


• • * 


. • • 


• • • 


59 


10 


70 


20 


11.66 


66.80 


21.54 


. • 




. 


60 




70 


30 


^ , 


67.40 


32.60 


Not analj 


^zed 


61 


26 


80 




23.41 


76.59 


. . . 


• • • . • . 


. . 


62 


10 


80 


id 


11.81 


77.29 


10.90 


• • • • . . 


. . . 


63 




80 


20 


. , . 


78.00 


22.00 


Not analy 


zed 


64 


id 


90 


, , 


11.96 


88.04 


. . . 


• • • . . . 


. . . 


65 




90 


10 


• • • 


88.86 


11.14 


Not analj 


'zed 


66 


. . . 


100 


. . . 


. . . 


10( 


).( 


)0 




. . . 


98.21 





*No. 6 was made up to be 50 per cent copper and 50 per cent nickel by weight. 
t Determined by difference. 



12 ILLINOIS ENGINEERING EXPERIMENT STATION 

shows that there was a remarkable loss in chromium in the chromium- 
copper alloys. The highest chromium content found was in No. 22 
which showed 13.15 per cent, whereas it should have shown about 17 
per cent. In No. 31 the chromium should have been about 26 per cent, 
but analysis showed only 9.89 per cent. All attempts to prepare 
alloys of chromium and copper containing higher percentages of chro- 
mium failed. Even in the case of Alloy No. 12, which was slowly 
cooled and which contained only 6.08 per cent of chromium, there is 
a separation of pure chromium or of a chromium-rich constituent. 
(See Fig. 25.) 

It has been stated by Hindrichs that at higher temperatures chro- 
mium and copper form an emulsion in which the chromium may be 
in a finely divided condition, and that on slow cooling the chromium 
collects in larger particles. It seems more probable, however, that 
chromium should be more soluble in copper at higher temperatures 
than at the melting point. In either case rapid cooling would tend 
to prevent such a separation and to produce a more homogeneous 
structure. Evidence to this effect is shown b}^ the fact that the alloy 
containing 10 per cent of chromium and 90 per cent of copper which 
is offered for sale by the Goldschmidt Thermit Company is almost 
homogeneous. This alloy is said to be made by an aluminothermic 
method. The aluminothermic reaction produces a very high tempera- 
ture, and if, as appears to be the case, the alloy is cooled suddenly, 
there would not be sufficient time for the separation of the chromium 
or chromium-rich constituent. 

In the case of the other alloys there were losses of different con- 
stituents depending upon a number of conditions. In the ternary 
alloys rich in copper there was generally a loss in chromium, probably 
due to the insolubility of the chromium in the other metals present. 
In the ternary alloys rich in nickel and in the binary alloys of chro- 
mium and nickel, there was generally a loss of nickel, but that may be 
accounted for by the fact that in making up the charges precaution 
was taken to protect the chromium by putting it in the bottom of the 
crucible, thus the nickel was left more exposed to oxidation. The 
changes in composition may be studied in Table 1. It is certain that 
in making a series of alloys by such a method as has been outlined, 
it is not safe to assume that the composition of the alloy obtained will 
be the same as that of the charge melted. 

11. Alloy of 50 Per Cent Cr and 50 Per Cent Cxi. — In order to 
determine whether or not a homogeneous alloy containing equal parts 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 13 

of chromium and copper could be prepared, the following experiments 
were conducted. 

A charge of 30 grams of chromium and 30 grams of copper was 
heated in an electric furnace. A little copper was put in the bottom 
of the crucible, the chromium was added, and then the remainder 
of the copper. The charge was covered with cryolite. It was heated 
well above the melting point of chromium and kept at that tempera- 
ture for at least fifteen minutes. The current was then shut ofp and the 
furnace allowed to cool slowly. An examination showed that the chro- 
mium had been melted. The copper which had been put on top of 
the charge was found at the bottom of the melt, and a fairly well 
defined line of separation between the copper-rich and the chromium- 
rich parts of the melt could be seen. (See Figs. 2 and 3.) The above 
experiment was later repeated with similar results. By this method 
it has been possible to get a division of the melt into two fairly well 
defined layers. From a microscopic examination (Figs. 2 and 3) it 
was evident that the lower layer contained some chromium, and it 
appeared that the upper layer contained some copper. Hindrichs 
stated that he was not able to get the two metals to separate into 
two sharply defined layers. 




Fig. 2 



Fig. 3 



MlCROPHOTOGRAPHS SHOWING SEPARATION OF COPPER FROM CHROMIUM IN A 50 PER 

CENT Cu, 50 Per cent Cr. Alloy. Etched in 1 per cent FeClj in 1: 1 HCl 

AND then Stained in I in Alcohol. The Dark Portion is the 

Copper-rich Constituent. Magnified 30 Diameters. 



14 ILLINOIS ENGINEERING EXPERIMENT STATION 

III. Physical and Mechanical Properties 

12. Color and Appearance. — The colors of the different alloys 
depend upon the amount of copper as compared with the sum of the 
amounts of chromium and nickel present. The chromium and nickel 
colors are more persistent than the copper color, and an alloy con- 
taining 50 per cent of copper and 50 per cent of nickel, or of chromium 
and nickel, has the color of nickel and does not show any color of 
copper. The alloys near the pure copper corner of the diagram (see 
Fig. 4) show the greatest tendency to tarnish when exposed to the 
air in the laboratory. On the other hand, the alloys near the nickel 
corner of the diagram are more porous and more likely to contain 
blowholes. 

13. MetJiod of Plotting Diagrams. — The following method has 
been adopted for plotting the relation between the compositions and 
the various properties of the alloys as shown in Fig. 4. 

The three metals, chromium, copper, and nickel, are represented 
by the corners of the equilateral triangle. The compositions of the 
different alloys, as found by analysis, have been represented by the 
centers of the circles so that they can be read directly from the dia- 
gram. The number of the alloy has been placed inside of the circle. 
All of the binary alloys fall on the sides of the triangle and all of the 
ternary alloys fall within the triangle. One example will serve to 
show the method of reading the composition of the different alloys 
from their positions on the diagram. No. 28 is approximately on the 
line marked 20 per cent chromium which runs parallel to the copper- 
nickel side of the triangle and between the lines marked 60 and 50 
per cent of nickel which run parallel to the chromium-copper side of 
triangle. Therefore it can be estimated that the alloy contains approx- 
imately 57 per cent of nickel. About 23 per cent is left for copper. 
The same result can be read from the distance of the center of the 
circle to the line marked 20 per cent copper which runs parallel to 
the chromium-nickel side of the triangle. By this method it is possible 
to read directly the composition of any alloy which has been plotted 
on the diagram. The alloys which show the copper color are Nos. 2, 
3, 4, 5, 12, 13, 14, 22, 23, 31, 32, 40, and 48. Their compositions can be 
read from Fig. 4 or can be found in Table 1. Table 2 shows in a brief 
way the kinds of castings which were obtained for the different alloys. 

14. Specific Gravity. — The specific gravities of the different 
alloys, as cast, are given in Table 2, and the same results are shown 
in Fig. 4. In the diagram the specific gravity of the alloy has been 
written above the circle representing the composition of the alloy. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 15 



The alloys were weighed in air and in distilled water at 25 degrees C, 
and the specific gravities were determined from the formula : 



Sp. gr. 



Wt. in air atPCx sp. gr. B.fi at PC. 



Loss of wt. in H^O at ^^C. 



>-\PureCr 
#^/ \/ \/ \/ \^ %, 

t A/ V V V \/'\A- 
z t /\ 7\ /\ ®\ Tx/K ^^ 

40 1 -V Y Y ,y ®\A^^ ^ 

•^ A 7\ 7\ ®A eJfA 7\ A 

. / \ /63d\ / y/v \/\/\/\(\ 

'^/ \/^\/ \/ <S>^A / \ Z /?T/r \ / \ r 

A 7\^ A ^ 
& / \ / \5©^ \ ^ \ / \ / \ / \ AA ^ 

^^##^W ;a A^4( A )( X A 

rs9\fito \lJacT\ vJ/y \ / \ / \ "*^ /\ /\ /\ /\ /\ 

yjcja/o yOJ/\ / \ / \ / \ / \ / \ / \ / \ / \ 

PureCu Pure Ni 

Fig. 4. Diagram Showing Composition of Alloys and Specific Gravities at 

25 Degrees C. 

If the alloys containing a constant amount of chromium with vary- 
ing amounts of copper and nickel are considered, it will be seen that 
there is little variation in the specific gravity. On the other hand, if the 
alloys containing a constant amount of copper with varying amounts 
of chromium and nickel are considered, it will be seen that the specific 
gravity decreases as the percentage of chromium increases. Similar 
results may be obtained if the alloys containing constant amounts of 
nickel and varying amounts of chromium and copper are examined. 
If the specific gravities are plotted as ordinates and the percentages of 
chromium as abscissae, fairly regular curves will be obtained. When 



16 



ILLINOIS ENGINEERING EXPERIMENT STATION 



Table 2 
Hardness, Specific Gravity, and Kind of Casting 





Diameter 


Brinell 


Specific 




Number 


of 


Hardness 


Gravity 


Kind of Casting 




Impression 


Number 


at 25° C. 




1 


. . . • • . 




Good. 


2 


Broke in test. 


8.56 


Good. 


3 


Cracked in test. 


8.76 


Medium. 


4 


Cracked in test. 


8.92 


Blowholes in places. 


5 


Specimen too small. 


8.76 


Blowholes in places. 


• 6 


Specimen too small. 


8.78 


Good. 


7 


7.20 


Below 68 


8.53 


Good. 


8 




• ■ • 


• - « 


Casting had blowholes. 


9 


• • • 


. • . 


. • • 


Blowholes all through. 


10 


• . • 


. . • 


• . . 


Blowholes in places. 


11 


Broke in test. 

(5.4 mm. thick) 


8.69 


Large crystals and small blowholes. 


12 


7.20 


Below 68 


8.78 


Good. 


13 


6.30 


86 


8.57 


Sound. 


14 


5.80 


103 


8.81 


Sound. 


15 


5.00 


143 


8.72 


Sound. 


16 


4.73 


161 


8.75 


Small, but sound. 


1 7 


4.70 


163 


8.62 


Fair. 


J. 1 

1 1^ 




• • • 




Small blowholes. 


J. o 

19 


.' '. '. 


• . • 


• • • 


Fair, except for blowholes. 


20 




. • • 




Fair, except for blowholes. 


21 




• • • 


• . • 


Large blowholes. 


22 


6.90 


69 


8.60 


Sound throughout. 


23 


6.40 


82 


8.71 


Good. 


24 


6.20 


89 


*8.34 


Good. 


25 


5.90 


99 


8.62 


Good. 


26 


4.80 


156 


8.52 


Very good. 


27 


4.50 


175 


8.54 


Sound. 


28 


4.50 


179 


8.50 


Sound. 


29 


5.30 


126 


8.48 


Sound. 




(Specimen small) 






30 








Large blowholes. 


31 


7.30 


68 


8*47 


Medium. 


32 


5.46 


117 


8.55 


Small, but sound. 


33 


5.50 


116 


8.49 


Excellent. There was some segregation 
of Cr at top of casting. 


34 


5.30 


126 


8.42 


Good. 


35 


4.92 


148 


8.34 


Excellent. 


36 


4.60 


170 


8.34 


Excellent. 


37 


4.70 


163 


8.36 


Excellent. 


38 


4.48 


181 


8.23 


Good. 


39 


Not prepared. 






40 


5.40 


121 


8.33 


Small, but sound. 


41 


5.50 


116 


8.38 


Good. 


42 


5.20 


131 


8.14 


Excellent. 


43 


4.80 


156 


8.12 


Excellent. 


44 


4.70 


163 


8.13 


Excellent. 


45 


4.93 


147(?) 


8.14 


Good. 




(Cracked in test.) 






46 


Not prepared. 




. 


47 


Not prepared. 






48 


5.70 


107 


8.24 


Excellent. 


49 






. . • 


Sound. 


50 


4.25 


202 


7.89 


Good. 


51 


4.50 


179 


7.95 


Good. 


55 


4.00 


228 




Sound. 


56 


4.50 


179(?) 


. . . 


Sound. 




(Specimen too small) 






60 




• • • 


• . • 


Sound. 


63 


• • • 


• • • 


• • • 


Sound. 


65 


. . • 


• • • 


. • • 


Sound. 



*This value is in error because of a concealed blowhole. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 17 

the exact composition of the alloy is known, it is possible to get some 
idea of the relative porosity of the specimen by a study of the specific 
gravity. 

15. Brinell Hardness Number. — The hardness measurements 
were made in the Materials Testing Laboratory of the Department of 
Theoretical and Applied Mechanics of the University of Illinois by 
using a Brinell instrument wdth a 3,000 kilogram load and a ball of 10 
mm. diameter, the pressure being applied for 15 seconds. The diameters 
of the impressions were carefully measured, and the hardness 
numbers corresponding to those diameters were found in a table sup- 
plied by the makers of the instrument. The pieces tested had been 
ground smooth and were from 4 to 8 mm. thick and about 20 mm. in 
diameter. Only one test was made on each piece, and if it was noticed 
that the piece had bulged or cracked from the pressure, that fact was 
recorded or the results were rejected. 

Specimen No. 11 requires special mention. It was a sample of 
pure nickel which had been melted in a magnesia crucible and slowly 
cooled. It had very large crystals (see microphotograph of Alloy No. 
11, Fig. 24), and when a piece 5.4 mm. thick and 22 mm. in diameter 
was tested, it broke at a load of about 2,000 kilograms. 

A comparison with the values which are given in Table 3* shows 
that some of the specimens were especially hard. 



Table .3 
Hardness Tests by Canada Department of Mines 



Material 


Date 


Load 


Brinell 
Hardness 


Copper, rolled sheet, unannealed 


Jan. 1913 


1,000 lbs. 


65.6 


" " " " 


" 1914 


1,000 " 


67.4 


)) j> >> »> 


" 1914 


3,500 " 


75.0 


II )> i> >) 


" 1914 


3,500 " 


81.9 


Swedish iron 


Jan. 1913 


3,500 " 


90.7 


u »» 


" 1914 


1,000 " 


68.6 


>» »I 


" 1914 


3,500 " 


75.2 


Wrought iron 


Jan. 1913 


3,500 " 


92.0 


>) >> 


" 1914 


1,000 " 


83.1 


»i »j 


" 1914 


3,500 " 


100.2 


Cast iron 


Jan. 1913 


3,500 " 


97.8 


'» " 


" 1914 


1,000 " 


84.4 


" " 


" 1914 


3,500 " 


104.5 


Mild steel 


Jan. 1913 


3,500 " 


109.9 


" " cold rolled shafting 


" 1914 


3,500 " 


126.2 


Tool steel 


Jan. 1913 


3,500 " 


153.8 


" " "Crescent" 


" 1914 


3,500 " 


130.2 


Spring steel 


Jan. 1913 


3,500 " 


160.3 




" 1914 


3,500 " 


178.0 


Tool steel self-hardening 


Jan. 1913 


3,500 " 


180.0 


"Rex" (before hardening) 


" 1914 


3,500 " 


162.1 


Tool steel, self-hardening 








"Rex" (after hardening) 


" 1914 


3,500 " 


240.0 


Tool steel, self-hardening, from work shop 








(School of Mines) 


Jan. 1914 


3,500 " 


259.0 


Cobalt 




3,500 " 


124.0 



*Canada Department of Mines, Report No. 309, Part II, p. 9, by Kalmus and Harper. 



18 ILLINOIS ENGINEERING EXPERIMENT STATION 

It is evident that some of these alloys are as hard as tool steel, 
and No. 55 approaches the hardness of self -hardening tool steel after 
hardening. It is likely that some of the alloys in the series have still 
greater hardness than the one referred to since some of the others 
contain more chromium. 

These specimens were extremely difficult to work. A saw blade 
was ruined on some of them without cutting more than 1 mm. deep. 
It has been found that by keeping the saw blades moist with turpen- 
tine they will last somewhat longer. 

The results obtained by the hardness tests are shown in Table 2. 

16. Tensile StrengtJi and Stress-Deformation Tests. — Eighteen 
specimens of the alloys of various compositions were turned down to 
test pieces and their ultimate tensile strengths determined. In all 
except two cases their elongations under stresses were measured. 

Test Pieces. — The test pieces which were from 3 to 4 inches in total 
length were turned to a diameter of approximately 0.300 inches for 
a length of 2.0 inches, and were threaded at the ends so that they could 
be screwed into half -inch grips. It was necessary to make the meas- 
urements on these short test pieces instead of the usual 8-inch speci- 
mens, because the original castings were only 4 to 5 inches long and 
pieces had been cut off for microscopic examination, for corrosion 
tests, etc. It is likely that some of the irregularities observed in the 
values obtained for the modulus of elasticity and for the ultimate 
tensile strength should be attributed to the use of the short test pieces. 

Testing MacJiine and Method of Loading. — The testing machine 
on which the tests were made was an Olsen Universal Screw-Power 
Testing Machine of 10,000 pounds capacity. The loading was by hand 
and was slow except in the case of specimens No. 17 and No. 28 
when the loading was done with the motor. The loading was con- 
tinuous and not repeated. 

Extensometer. — A Ewing extensometer having a gage of 1.25 
inches was used in measuring the elongations. The instrument was 
sensitive and the elongations could be read accurately to 0.00008 
inches and estimated to 0.000008 inches. The initial or zero extenso- 
meter reading was taken with a small load on the machine. After a 
satisfactory number of readings had been made the extensometer was 
removed and the load increased until the specimen broke. 

Calculation of Modulus of Elasticity. — ^^Curves were plotted with 
stresses as ordinates and elongations as abscissae. Tangents to the 
curves were drawn and extended to a point which corresponded to an 
elongation of 0.001 inch on a length of 1.0 inch, and the stress cor- 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 19 

responding to that elongation was read from the cross-ruled paper. 
This stress minus the initial stress for zero elongation gave the modulus 
of elasticity. The values are given in round numbers. 

The results are shown in Table 4, and the specimens have been 
tabulated so that the percentage of chromium increases from the top 
to the bottom of the column. 

Table 4 
Composition, Modulus of Elasticity, and Ultimate Tensile Strength 





Composition of the Alloy 


as Found by 


Moduhis of 


Ultimate Tensile 


Number 




Analysis 




Elasticity in 
lb. per sq. in. 


Strength in lb. 




Cr 


Cu 


Ni 


per sq. in. 


14 


8.25 


74.63 


16.05 


18,000,000 


19,978 


17 


10.18 


42.56 


48.00 




23,833 


25 


13.62 


66.92 


19.20 


7,000,000 


14,880* 


24 


14.56 


56.30 


29.24 


20,000,000 


17,521 


26 


19.30 


44.08 


36.34 


12,000,000 


14.802 


28 


19.64 


22.20 


57.36 




56,255 


29 


19.64 


10 88 


68.62 


7,000,666 


19,846t 


33 


22.00 


59.26 


19.48 


17,600,000 


22,650 


34 


25.10 


45.70 


28.52 


20,000,000 


25,768 


36 


28.10 


22.58 


48.42 


23,700,000 


32,654 plus 


38 


28.44 




71.56 


15,800,000 


36,958 


35 


29.46 


33.76 


36.78 


16,300,000 


38,734 


37 


29.70 


10.90 


58.12 


22,000,000 


29,630 


42 


38.16 


33.60 


26.78 


26,400,000 


7,449 


44 


43.30 


11.02 


46.46 


16,300,000 


29,587 


49 


47.54 


24.12 


26.28 


43,200,000 


22,336 plus 


48 


54.92 


28.42 


17.12 


57,000,000 


33,842t 


51 


57.40 




41.66 


48,000,000 


37,200 



♦Showed a flaw at the fracture. 

fThe threads were not straight and these values are considered less reliable than 
the others. 

The following is given as a typical set of data. The complete data 
for each specimen is not included. 



Alloy No. 35 
Diameter 0.305 in. Cross section, 0.07306 sq. in. 



Extensometer 


Elongation in 


Load in 




Readings 


.0008 in. 


Pounds 




3.00 


0.0000 


150 


2,053 


3.30 


0.30 


380 


5,201 


3.63 


0.63 


625 


8,554 


3.93 


0.93 


894 


12,236 


4.23 


1.23 


1140 


15,603 


4.55 


1.55 


1385 


18,956 


4.83 


1.83 


1625 


22,241 


5.18 


2.18 


1790 


24,500 


5.60 


2.60 


2000 


27,374 


Ultimate 




2830 


38,734 



Remarks 



Reduction and Elongation. — The per cent of reduction of area was 
quite small in all cases, in fact, it was so slight that measurements with 
a micrometer would not give appreciable decreases in diameters. The 
curves in Fig. 5 show that the elongations were small. These alloys 



20 ILLINOIS ENGINEERING EXPERIMENT STATION 

do not show well-defined yield points or elastic limits but a gradual 
flattening of the stress deformation curves until the ultimate is 
reached. The curves are similar to those for cast iron. 

Ultimate Strength. — The ultimate tensile strength varied from 
7,449 to 56,255 pounds per square inch cross-section. The binary 
alloy of chromium and nickel had more ultimate tensile strength than 
the ternary alloy in which 10 per cent of the nickel had been replaced 
by copper. (See Nos. 38 and 37.) It does not seem possible, however, 
to draw any general conclusions from these results as to which com- 
position will have the greatest tensile strength. The remarkably low 
ultimate strength for No. 42 is probably due to the fact that it con- 
tains a large amount of chromium (38.16 per cent) and at the same 
time a large amount of copper (33.60 per cent), which produces an 
unstable condition because it has not been possible to prepare binary 
alloys of copper and chromium containing more than about 13 per 
cent of chromium. 

Modulus of Elasticity. — Although there are some irregularities 
in the values obtained, it seems that the modulus of elasticity increases 
with an increase in chromium content. The values obtained vary from 
15,000,000 to more than 40,000,000, or by from 1/2 to II/9 times the 
value for iron and steel. 

A general idea of the properties of these alloys may be obtained 
from the stress-deformation curves which are given in Fig. 5. 

IV. Corrosion Tests 

17. Reason for Tests. — In order to determine the power of the 
different alloys to resist corrosion, over three hundred tests were made. 
It was hoped that such a series of tests would show that some of these 
alloys were highly resistant to corrosion and suited for industrial 
purposes requiring that property. 

18. Materials. — The corroding reagents used were normal solu- 
tions of nitric acid, hydrochloric acid, sulfuric acid, sodium hydrox- 
ide, ammonium hydroxide, sodium chloride, and molten fatty acids. 
The normal solutions had been carefully standardized and were known 
to be reasonably accurate. The fatty acids were secured from Swift 
& Co. of Chicago and were listed as double distilled. An analysis 
showed that they had a mean molecular weight of 273, an iodine 
value of 72, and consisted of a mixture of fatty acids. The alloy 
specimens used in the tests were usually about 5 mm. thick and about 
15 to 20 mm. in diameter. They were ground and then polished with 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 21 



20000 




























18000 
16000 
14000 








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.001 .002 .003 .004 .00/ .002 .003 .004 .00/ .002.003 

Unit £/ongQt/on - inches 

Fig. 5. Stress Deformation Curves for Cr-Cu-Ni Alloys. 



22 ILLINOIS ENGINEERING EXPERIMENT STATION 

No. 000 Hubert Emery paper. The three metals were included in the 
tests with the alloys. Fifty different samples were tested. 

19. Mefhods. — There does not seem to be any well-established 
method for making corrosion tests. Different investigators have used 
a variety of methods. For the work in hand, the scheme used has been 
reasonably satisfactory and it will be described somewhat in detail. 

Solutions. — In the case of the normal solutions mentioned under 
Section 18, 400 cc. were used for each test. No attempt was made to 
remove any dissolved gases, such as carbon dioxide. The solutions 
were contained in beakers of such size that they were filled almost to 
the top. Of course, the solutions changed slightly in concentration 
because of evaporation and of corrosion of the specimens, but that 
could not be avoided. The loss by evaporation was made very small 
by covering the beakers with watch glasses. With such a large volume 
of solution the change in concentration was not important in most 
cases. If it was observed that a specimen was dissolving very rapidly, 
it was removed and from the amount which had been corroded a 
calculation was made to find how much would have corroded in one 
week. One hundred grams of the fatty acids were taken for each of 
the tests that were made at 105 degrees C. and 200 grams for those 
made at 85 degrees C. 

Suspending tJie Specimens. — Cotton thread was used to suspend 
the specimens in the alkaline solutions and wool thread was used in 
the acid solutions. The specimens were completely immersed in the 
liquid so that no part was in contact with the air. In some cases there 
was a tendency for the solutions to creep out of the beakers by way 
of the threads, but that was prevented by putting a little paraffin 
on the thread. 

Temperature. — The corrosion tests were made at the temperature 
of the laboratory. In order to be able to approximate the mean tem- 
perature, a maximum and minimum thermometer was kept on the 
desk where the tests were being made and readings were taken from 
time to time. A calculation showed that the mean temperature for 
the whole period of time was 20 degrees C. 

Time. — It was intended to leave the specimens in the solutions 
for one week, but in some cases it was necessary to remove them 
before the end of that period. 

Calculations. — The amount of surface exposed to corrosion was 
determined by measuring the thickness and the diameter of the piece 
to the nearest 0.1 mm. and then calculating the total surface. Unless 
there was known to have been a big loss in corrosion, the surface was 



A STUDY OF THE ALLOYS OP CHROMIUM, COPPER, AND NICKEL 



23 



not recalculated when the piece was used for a second test. The 
results have been calculated to loss in weight per week per square 
inch of surface exposed and have been expressed in milligrams. 

Accuracy of the MetJiod. — The accuracy of the method has not 
been all that might be desired. The specimens were weighed before 
and after the tests and the loss in weight was taken as the loss due to 

,00 -@ZeCr 

^0/ \/ \/ \S^ 

/ V \/\/\/\ ^^ \ 

,, I / ' / y Y . y Y "%^ % 

.0 1 — % ( V y^^ i^-Bm,p 

,0 j / W'Sy \M^^^Sf\( \ t 

0";#A €A%AA^ /4y MAkr\^ 

Md ^ ezr^ ^^'i^ r^i-^ (H'"^ kin"^ h f^^' \/ i^^^ /^^fe < ^^7o} 

PureCu POreffi 

Fig. 6. Diagram Showing Composition of Alloys and Corrosion in Normal 

Nitric Acid Solution. 



corrosion. In a few cases a gain in weight was observed. It was hard 
to get all of the salts, etc. out of some of the porous pieces, but by 
boiling in distilled water and drying at 100 degrees C. most of that 
trouble was avoided. While some of the results show irregularities, 
as a whole they may be considered reasonably accurate and reliable. 
20. Results. — The results of the corrosion tests are shown on tri- 
angular diagrams as explained previously (p. 14). In each diagram 
the loss in weight in milligrams per square inch per week for each 



24 



ILLINOIS ENGINEERING EXPERIMENT STATION 



alloy tested is shown above the circle, the center of which represents 
the composition of the alloy as determined by analysis. 

Complete data of the tests with normal nitric acid are given in 
Table 5, and by comparison of this table with the corresponding dia- 
gram (Fig. 6), the method of plotting can be readily understood. 
Such detailed data has been omitted for the tests with other solvents, 
the results being shown only in the graphical form. Areas of minimum 
corrosion are designat-ed on the diagrams by shading. 



^6976.4 
100 m^PureCr 

% .(aV /\/\/\/\ A 

I ^* ^0 / y \/ Y \ ^Q %^ 

"^ ■^^'^ "TV /\j^ j\ 7\ /%) ^' 

,0 y y y A / AX^y ^ 

^Q ^^^ ^^CL ^ ^ ^^^ V^ 

##?y^/\ /V7\ A A /\ A 

PureCu PursNi 

Fig. 7. Dlvgram Showing Composition of Alloys and Corrosion in Normal 

Hydrochloric Acid Solution. 



Nitric Acid. — Table 5 and Fig. 6 show the results obtained with a 
normal solution of nitric acid. Nickel, especially, is attacked, and 
alloys with high percentages of this metal show great corrosion. In 
the chromium-nickel alloys there is a gradual decrease in the loss by 
corrosion as the per cent of chromium increases, with an abrupt drop 
at Alloy No. 45. There is also a marked change in the micro-structure 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 25 



Table 5 

Corrosion in Normal Nitric Acid 



■■ 






Loss in 


Surface 1 


Time in 


Loss in wt. in mg. 


Number 


"Weight 
Before 


Weight 
After 


weight 
mg. 






solution 
hrs. 


per wk. 


sq. in. 


sq. cm. 




sq. in. 1 


sq. cm. 


1 


5.5125 


5.4945 


18.0 


0.71 


4.58 


138 


30.80 


4.78 


2 


8.6232 


8.5882 


35.0 


1.08 


6.67 


138 


41.40 


6.42 


3 


5.6478 


5.6323 


15.5 


0.68 


4.41 


138 


27.70 


4.30 


4 


4.5331 


4.5205 


12.6 


0.61 


3.95 


138 


25.10 


3.38 


5 


4.5007 


4.4898 


10.9 


0.64 


4.12 


138 


21.40 


3.33 


6 


4.5918 


4.5859 


5.9 


0.63 


4.04 


138 


11.40 


1.77 


7 


16.9032 


16.8890 


14.2 


1.52 


9.83 


138 


11.40 


1.77 


8 


11.3342 


11.3092 


25.0 


1.36 


8.77 


138 


22.40 


3.47 


9 


9.8259 


9.8086 


14.5 


1.28 


8.27 


138 


14.80 


2.13 


10 


10.0842 


10.0724 


11.8 


1.24 


7.98 


138 


11.60 


1.80 


11 


9.8700 


9.4410 


429.0 


1.32 


8.49 


24 


2270.00 


352.00 


12 


11.7920 


11.7783 


13.7 


1.33 


8.58 


137 


12.60 


1.98 


13 


13.1763 


13.1647 


11.6 


1.35 


8.69 


137 


10.40 


1.62 


14 


10.0412 


10.0310 


10.2 


1.16 


7.47 


137 


10.80 


1.67 


15 


8.4206 


8.4123 


8.3 


1.03 


6.66 


137 


9.90 


1.53 


16 


7.3881 


7.3807 


7.4 


1.07 


6.94 


137 


8.50 


1.32 


17 


12.8800 


12.8684 


11.6 


1.32 


8.51 


137 


10.80 


1.67 


18 


10.5626 


10.5474 


15.2 


1.24 


7.98 


137 


15.10 


2.33 


19 


14.3148 


14.2931 


21.7 


1.54 


9.92 


137 


17.20 


2.67 


20 


10.6661 


10.6490 


17.1 


1.18 


7.61 


137 


17.80 


2.76 


21 


13.2433 


12.8326 


410.7 


1.47 


9.43 


48 


980.00 


152.00 


22 


9.0392 


9.0390 


10.2 


1.07 


6.91 


122 


13.10 


2.03 


23 


9.1265 


9.1151 


11.4 


1.03 


6.67 


122 


16.30 


2.22 


24 


10.5944 


10.5821 


12.3 


1.26 


8.10 


122 


13.40 


2.08 


25 


11.1470 


11.1376 


9.4 


1.23 


7.92 


122 


10.50 


1.63 


26 


13.1489 


13.1412 


7.7 


1.39 


8.95 


122 


7.60 


1.18 


27 


9.7288 


9.7222 


6.6 


1.08 


7.00 


168 


6.20 


0.95 


28 


9.8098 


9.7948 


15.0 


1.17 


7.56 


122 


17.70 


2.74 


29 


8.0788 


8.0655 


13.3 


1.03 


6.65 


122 


18.10 


2.80 


30 


Too many 


lioles. 














31 


11.1653 


11.0955 


69.8 


1.16 


7.46 


168 


60.30 


9.35 


32 


12.1926 


12.1777 


14.9 


1.38 


8.92 


168 


10.80 


1.67 


33 


9.7367 


9.7270 


9.7 


1.29 


8.33 


168 


7.50 


1.16 


34 


11.6059 


11.5994 


6.5 


1.37 


8.82 


168 


4.80 


0.74 


35 


8.8904 


8.8847 


5.7 


1.18 


7.62 


168 


4.80 


0.74 


36 


9.6290 


9.6241 


5.9 


1.20 


7.73 


168 


4.90 


0.76 


37 


10.8796 


10.8738 


5.8 


1.31 


8.43 


168 


4.90 , 


0.76 


38 


9.2554 


9.0129 


242.5 


1.18 


7.62 


70 


492.00 


76.00 


39 


Not prepar 


ed. 














40 


13.7427 


13.7295 


13.2 


1.45 


9.33 


168 


9.20 


1.43 


41 


11.5077 


11.4963 


11.4 


1.37 


8.83 


168 


j 8.30 


1.29 


42 


10.1818 


10.1725 


9.3 


1.28 


8.23 


168 


1 7.30 


1.13 


43 


11.5401 


11.5341 


6.0 


1.35 


8.70 


168 


1 4.40 


0.69 


44 


11.8160 


11.8146 


1.4 


1.37 


8.81 


168 


1.02 


0.16 


45 


10.5332 


10.5325 


0.7 


1.16 


V.4P 


168 


0.60 


0.09 


46 


Not prepar 


ed. 














47 


Not prepar 


ed. 














48 


10.7279 


10.7154 


12.5 


1.29 


8.32 


168 


9.70 


1.50 


49 


9. 19 10 


9.1854 


5.6 


1.21 


7.81 


122 


6.40 


0.99 


50 


10.4293 


10.4198 


9.5 


1.28 


8.23 


168 


7.40 


1.15 


51 


12.4458 


12.4458 


0.0 


1.42 


9.19 


168 


0.00 


0.00 


55 


9.7665 


9.7559 


10.6 


1.38 


8.89 


168 


7.70 


1.19 


56 


8.4517 


8.4513 


0.4 


1.14 


7.33 


168 


0.35 


0.05 


66 


2.0776 


2.0774 


0.2 


0.57 


3.66 


168 


0.35 


0.05 



26 



ILLINOIS ENGINEERING EXPERIMENT STATION 



of the alloys in the same region as may be seen by comparing micro- 
photographs of Alloys No. 11, 21, 30, 38, and 45. (Figs. No. 24, 34, 43, 
51, and 58.) 

HydrocJiloric Acid. — The results from these tests are shown in 
Fig. 7. It will be seen that all of the metals showed considerable 
corrosion in hydrochloric acid and that chromium was especially 







Pure Cu PureNi 

Fig. 8. Diagram Showing Composition of Alloys and Corrosion in Normal 

Sulfuric Acid Solution. 

soluble in this acid. However, there is a fairly well-defined area in 
the triangle over which the corrosion was small. 

Sulfuric Acid.— The data obtained from the corrosion tests in 
normal sulfuric acid are shown in Fig. 8. The results do not require 
any special explanation. 

Sodium Hydroxide. — Fig. 9 shows the results obtained by the 
corrosion tests in normal sodium hydroxide. Copper and nickel show 
appreciable losses, while chromium is little attacked. In general the 
losses for the alloys are small. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 27 

Ammonium Hydroxide. — The alloys which best resist corrosion by 
ammonia are near the nickel corner of the triangle and on the chro- 
mium-nickel side. The results are shown in Fig. 10. 

The copper-chromium and the copper-rich alloys show a selective 
corrosion in ammonium hydroxide; that is, the copper is removed 



^ .^ Y \/\/\/\ tg % 

S / A 7\ /\ W\ 7v 7)^ \ 

"^ /\ 7\ A W\ /\ A A 

'' 7 \ A A ^W\ ®Ai^^ A ) ^ 

^/ ^ W v ^^w V ^^/ ^^A^^^ 

PureCu PureNi 

Fig. 9. Diagram Showing Composition of Alloys and Corrosion in Normal 

Sodium Hydroxide Solution. 



and some of the chromium is left. This fact suggests that good re- 
sults might be obtained by using ammonia as an etching reagent in 
the preparation of specimens for microscopic examination. 

Sodium Chloride. — Losses in normal sodium chloride solution are, 
in general, small. These losses are largest for alloys near the copper 
corner of the triangle. (See Fig. 11.) 

Fatty Acids. — Only twenty-four specimens were corroded in the 
fatty acids. Twelve of the tests were made at 105 degrees C. by hea^ 
ing in an electric oven. The other tests were made at approximately 



28 



ILLINOIS ENGINEERING EXPERIMENT STATION 



85 degrees C. by heating on a steam bath. The results are shown in 
Fig. 12. The greatest losses are near the copper corner of the tri- 
angle. This suggests that instead of using a copper container for 
fatty acids it might be advisable to use an alloy of copper and nickel, 
or possibly one containing copper and nickel with a little chromium. 



5?) 4 



'% 




PureCu ^ PureM 

Fig. 10. Diagram Showing Composition of Alloys and Corrosion in Normal 

Ammonium Hydroxide Solution. 



Comparison of Corrosions. — Table 6, page 31, shows the relative 
corrosions in the different reagents which have been used. The values 
are losses in weight in milligrams per square inch per week. 

21. Conclusions. — The corrosion tests show that the amount of 
loss in the different reagents is not proportional to the strengths of 
the different acids or bases. 

So far, it has not been possible to show any definite relation be- 
tween the relative electromotive forces and corrosion losses. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 29 



Table 6 
Comparison of the Corrosions in the Different Solutions 

THE VALUES ARE LOSS IN WEIGHT IN MILLIGRAMS PER WEEK PER SQUARE INCH 



Number 


NaCl 


HCl 


H2SO4 


HNO3 


NaOH 


NH4OH 


Fatty acids 


1 


5.08 


45.0 


31.00 


30.80 


15.00 


41.80 


8.90 


2 


4.18 


20.0 


19.50 


41.40 


5.90 


46.40 


. . . 


3 


1.60 


34.2 


18.40 


27.70 


None 


46.30 


5.80 


4 


1.65 


29.4 


19.00 


25.10 


None 


37.30 


. . . 


5 


2.35 


26;7 


17.00 


21.40 


0.16 


18.80 


2.90 


6 


2.37 


21.2 


15.10 


11.40 


0.16 


0.00 




7 


0.78 


7.1 


19.30 


22.40 


1.10 


2.20 




8 


1.71 


23.0 


17.40 


11.40 


0.13 


33.60 


4.66 


9 


1.71 


16.5 


11.70 


14.80 


2.60 


15.20 




10 


1.13 


18.2 


16.40 


11.60 


0.32 


0.97 


. . . 


11 


None 


207.0 


19.40 


2270.00 


18.70 


15.90 




12 


4.33 


42.8 


17.20 


12.60 


10.40 


41.80 


16.56 


13 


2.55 


28.6 


14.90 


10.40 


6.60 


45.20 


. . . 


14 


1.89 


6.3 


11.90 


10.80 i 


0.26 


33.70 


7.70 


15 


1.53 


4.8 


14.00 


9.90 


0.10 


34.40 


. . . 


16 


0.66 


6.0 


5.10 


8.50 


0.00 


14.30 


. . . 


17 


0.53 


4.6 


6.70 


10.80 


0.00 


0.23 


Noue 


18 


0.71 


8.2 


5.30 


15.10 


2.60 


3.60 




19 


0.63 


7.3 


12.30 


17.20 


2.70 


0.97 


I'.ii 


20 


0.60 


10.7 


4.90 


17.80 


None 


0.76 


. . . 


21 


None 


19.4 


6.00 


980.00 


2.70 


2.65 


. . . 


22 


4.00 


38.3 


14.20 


13.10 


9.60 


57.80 


. . . 


23 


3.65 


29.5 


14.50 


16.30 


5.00 


47.70 


6.40 


24 


0.76 


33.3 


9.00 


13.40 


None 


29.50 




25 


2.13 


8.2 


4.10 


10.50 


1.20 


36.60 


6.60 


26 


0.94 


6.2 


3.70 


7.60 


0.14 


23.70 


3.80 


27 


0.85 


18.8 


9.40 


6.20 


None 


21.20 


0.87 


28 


0.37 


4.4 


4.10 


17.70 


0.00 


0.26 




29 


0.51 


6.1 


7.40 


18.10 


0.00 


0.00 


0.25 


30 


Too many blowholes. 












31 


4.60 


30.3 


16.40 


60.30 


0.86 


67.50 


10.70 


32 


3.30 


10.8 


15.60 


10.80 


6.90 


49.20 


. . . 


33 


2.62 


5.0 


6.10 


7.50 


0.64 


28.30 


7.50 


34 


1.37 


6.6 


5.30 


4.80 


0.58 


39.60 




35 


1.05 


12.3 


9.60 


4.80 


0.09 


35.60 


3.80 


36 


0.37 


11.6 


5.10 


4.90 


None 


29.50 




37 




5.9 


1.80 


4.90 


0.30 


None 




38 


0.37 


8.1 


4.10 


492.00 


0.00 


None 


8.30 


39 


Not prepared. 












40 


2.95 


15.2 


14.90 


9.20 


3.90 


50.80 


11.30 


41 


1.84 


7.5 


12.40 


8.30 


1.10 


41.40 


. . . 


42 


1.67 


11.5 


11.00 


7.30 


1.00 


37.50 


2.90 


43 


1.25 


18.6 


8.00 


4.40 


0.15 


31.50 




44 


0.45 


10.0 


1.30 


1.02 


0.22 


0.90 


0.34 


45 


0.40 


21.2 


2.20 


0.60 


0.53 


0.00 




46 


Not prepared. 












47 


Not prepared. 












48 


2.45 


16.2 


13.20 


9.70 


5.70 


44.80 


3.25 


49 


0.87 


9.5 


5.60 


6.4i) 


0.25 


25.30 


. . . 


50 


0.37 


19.5 


6.40 


■'{.4. ) 


1.00 


0.90 


2.40 


51 


0.27 


31.2 


0.35 


0.0) 


0.14 


, 0.00 




55 


0.33 


11.9 


3.70 


7.70 


1.00 


0.20 




56 


0.27 


32.2 


1.30 


0.35 


0.44 


0.50 




66 


2.00 


16976.4 


1.00 


0.35 


0.35 


1.60 


1.23 



30 ILLINOIS ENGINEERING EXPERIMENT STATION 

In all cases there are certain fairly well-defined ranges of com- 
position as shown in the diagrams in which the alloys are highly re- 
sistant to corrosion. 

Generally the ternary alloys are less corroded than the binary, 
though there are some exceptions. 

,00 (ee)^^ 

^0 / \^ 

90--- 

<h/\/\^ 

60—- 

^0/ \/ \/ \^ 
70 — 

^ "^0 / \/ \/ \/ \tP i 

\ 9 A 7\W7\ 7\ 7^ % 

30 — 

'^O/ hJp9'^ (33/ \/ ^?£k^^^^^^^S^^^»^ 
cO 



PureCu PureNi. 

Fig. 11, Diagram Showing Composition of Alloys and Cokrosion in Normal 

Sodium Chloride Solution. 




V. Relation Between Corrosion and Relative Electromotive 

Forces 

22. Purpose of Measurements. — A series of measurements was 
made of the relative electromotive forces developed by the different 
alloys when placed in contact with an electrolyte, to ascertain whether 
or not any simple relation could be found between the values obtained 
and the amount of corrosion sustained by the same alloys in the same 
electrolyte. The measurements were made in a sodium chloride solu- 
tion and the data obtained is of considerable interest, but it is not 
sufficient to afford a basis for any general conclusions. 



A STUDY OP THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 31 

23. MetJiod and Results of Measurements. — After some experi- 
mentation with other methods the Poggendorf Compensation Method* 
of measurement was chosen. Briefly described, it consisted in bal- 
ancing the current from two No. 6 French Auto Special Dry Batteries 
against the current from a calomel electrode and the alloy in contact 



^ y^«;^ / \ / ^y / \ / \ / ^\ t\ /I 

^ A X^X rX V^^^ K M 

Fig. 12. Diagram Showing Composition of Alloys and Corrosion in 

Fatty Acids 



with 4 Normal salt solutions. The resistance in the first circuit 
was 110 ohms. This resistance was varied in the second circuit until 
the galvanometer showed a zero deflection. A voltmeter, reading 
to 1.5 volts, was so connected that it showed directly the potential in 
the calomel electrode-alloy combination. In the different series of 
measurements all conditions remained the same, except that different 
alloys were placed in salt solution. Readings were taken at one 
minute intervals for five minutes. The results are shown in Table 7. 



*Stahler, A. Handb, d. Arbeitsmethoden in der anorg. Chem., 1914. 



32 ILLINOIS ENGINEERING EXPERIMENT STATION 

These values are not absolute, but relative, for they were made under 
the same conditions. The following factors seemed to influence the 
results: (a) The condition of the specimen as regards polishing, 
(b) The depth to which the piece was immersed in the solution. The 
latter factor was active until the piece was at least one-half covered ; 
after that the value did not seem to change even upon complete im- 
mersion, (c) The' time that the solution and specimen were left in 
contact, especially if any current was allowed to flow through the 
system. It is believed that this effect was caused by the deposition of 
gases upon the specimen or possibly by gases already dissolved in them, 
(d) Any moving of the specimen or solution. 

It was noticed that the alloys which contained high percentages 
of copper gave values which increased with time, whereas those contain- 
ing high percentages of nickel gave values which decreased with time. 
These results together with the composition of the alloys are shown 
diagrammatically in Fig. 13. Those alloys which showed an increase 
have been marked with a plus sign and those which showed a decrease 
have been marked with a minus sign. Alloys Nos. 17, 18, and 19 
seem irregular, but they contained blowholes; and if there was any 
concentration of the low melting constituent (copper) at the blow- 
holes, it might be expected that they would behave like the copper-ricli 
alloys. No. 24 is the only one which did not show a change in the 
five minute interval, although the changes shown by some of the others 
were very small. From an examination of the corrosion tables it may 
be seen that the alloys which showed little or no change in relative 
electromotive force were not immune to corrosion in the different 
solutions. Therefore, it does not seem that resistance to corrosion 
can be predicted from the fact that the relative electromotive force 
of the alloy in contact with an electrolyte either remained constant or 
showed little variation. 

In the case of the corrosions in normal salt solutions it was noticed 
that, almost without exception, the alloys which had shown an increase 
in the relative electromotive force were the ones which showed a 
turbidity of the corroding solution, while those which had given 
decreasing values remained clear. Similarly, in the corrosions in 
ammonium hydroxide the solutions were colored a deep blue in the 
case of the alloys which had shown increases in the relative electro- 
motive forces, while the others remained practically colorless. How- 
ever, when the corrosion specimens were weighed, it was found that 
there had been losses in the salt solutions, which had remained clear. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 33 

and in the ammonium hydroxide solutions, which had remained color- 
less. 

From the results obtained it is not felt that any safe conclusions 
can be drawn as to the possibility of predicting the corrodibility of 
an alloj^ from such a series of measurements of the relative electro- 
motive forces or from the changes in these values with time. 

6 / \ \0 
^o/\/\^ 

^/ \/ \/ \^^ 

JO V 

.1 / V v v v \i \ 

'^ ?t 7\ A A A A \ 

50-\ ^— -A X A ?VV A \ %■ 

^ \ A A 7 \ /k Ai % 

'^Z \/^\/ \/ jA/ \j^ \/ \^ 

'' -^ — ^^^^^^ — \%f^--^y-^ — ^ 

^o/ V w \f a/ V V V ^^ 

^^ -^ — m. — )\ ±)\ W\ - ^^ — ^ — ® — ^'^ 

io—m-—F^ — -^s^K^ — X X — ®) w/ VA/ 

2/ d/ '^) — (1/ ® C8^ ^ ^ Qo) Ui 

'^ure Cu Pure/// 

Fig. 13. Diagram Showing Composition of Alloys and Their Changes ix 
Electromotive Force in a 4 Normal Sodium Chloride Solution. 




VI. Thermal Analysis and Microscopic Examination. 



24. Difficulties of Thermal Analysis. — The very high meltinu' 
points of the metals and alloys of this system, their great susceptibility 
to oxidation and absorption of impurities at high temperatures, and 
the extreme difficulty of finding suitable materials for pyrometers, 
tubes, and crucibles, all combined to make the study of freezing point 
curves extremely difficult, and, so far as present developments arc 
concerned, almost impossible. 



34 



ILLINOIS ENGINEERING EXPERIMENT STATION 



Table 7 

Relative Electromotive Forces of the Different Alloys in Contact with 

4 Normal Salt Solutions 



Number 






Relative Electromotive Force After 




1 min. 


2 min. 


3 min. 


1 4 min. 


1 5 min. 


1 Change 


1 Remarks 


1 
2 


0.328 


0.328 


0.334 


0.331 


0.364 
0.331 


+ .003 


Increasing 


3 


0.328 


0.330 


0.331 


0.333 


0.334 


+ .006 




4 


0.311 


0.316 


0.317 


0.318 


0.319 


+ .009 




5 


0.314 


0.318 


0.315 


0.318 


0.315 


+ .001 




6 


0.309 


0.302 


0.296 


0.295 


0.293 


— .016 




7 


0.313 


0.315 


0.315 


0.318 


0.318 


-h .005 




8 


0.305 


0.300 


0.300 


0.297 


0.296 


— .009 




9 


0.295 


0.295 


0.290 


0.280 


0.280 


— .015 




10 


0.318 


0.309 


0.300 


0.294 


0.289 


— .029 




11 


0.294 


0.294 


0.290 


0.287 


0.287 


— .007 


Pure nickel 


12 


0.338 


0.341 


0.345 


0.346 


0.348 


+ .010 




13 


0.345 


0.343 


0.348 


0.348 


0.350 


+ .005 




14 


0.340 


0.341 


0.341 


0.339 


0.339 


— .001 




15 


0.348 


0.345 


0.344 


0.342 


0.341 


— .007 




16 


0.342 


0.336 


0.333 


0.332 


0.330 


— .012 




17 


0.310 


0.309 


0.306 


0.306 


0.304 


— .006 




18 


0.307 


0.304 


0.303 


0.303 


0.303 


— .004 




19 


0.306 


0.312 


0.315 


0.316 


0.318 


+ .012 




20 


0.331 


0.325 


0.315 


0.309 


0.300 


— .031 




21 


0.294 


0.282 


0.279 


0.276 


0.275 


— .019 




22 


0.357 


0.360 


0.363 


0.363 


0.363 


+ .006 




23 


0.345 


0.347 


0.348 


0.349 


0.349 


+ .004 




24 


0.307 


0.306 


0.307 


0.307 


0.307 


+ .000 




25 


0.315 


0.319 


0.322 


0.324 


0.325 


+ .010 




26 


0.336 


0.339 


0.339 


0.339 


0.339 


+ .003 




27 


0.330 


0.326 


0.320 


0.320 


0.320 


— .010 




28 


0.355 


0.344 


0.339 


0.332 


0.330 


— .025 




29 


0.360 


0.349 


0.341 


0.338 


0.332 


— .028 




30 


0.325 


0.320 


0.329 


0.331 


0.324 


— .001 




31 


0.339 


0.340 


0.345 


0.346 


0.349 


+ .010 




32 


0.330 


0.337 


0.339 


0.340 


0.341 


+ .011 




33 


0.341 


0.347 


0346 


0.346 


0.346 


+ .005 




34 


0.340 


0.339 


0.339 


0.338 


0.338 


— .002 




35 


0.333 


0.333 


0.334 


0.334 


0.334 


+ .001 




36 


0.334 


0.330 


0.329 


0.320 


0.320 


— .014 




37 


0.332 


0.330 


0.320 


0.319 


0.315 


— .017 




38 


0.316 


0.310 


0.305 


0.300 


0.296 


— .020 




39 
40 


0.342 


0.346 


0.352 


0.355 


0.355 


+ .6i3 


Not preparea 


41 


0.350 


0.351 


0.352 


0.355 


0.355 


+ .005 




42 


0.331 


0.335 


0.339 


0.339 


0.339 


+ .008 




43 


0.366 


0.365 




0.350 


0.346 


— .020 




44 


0.314 


0.300 


0.290 


0.286 


0.286 


— .028 




45 


0.322 


0.315 


0.309 


0.302 


0.300 


— .022 




46 

47 
48 


0.338 


0.345 


0.349 


0.35i 


0.350 


+ .012 


Not prepared 
Not prepared 


49 


0.345 


0.347 


0.349 


0.349 


0.349 


+ .004 




50 


0.298 


0.299 


0.298 


0.295 


0.295 


— .003 




51 


0.468 


0.473 


0.476 


0.480 


0.480 


+ .012 





Note: The other specimens have either not been prepared or have not been tested. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 6,^ 

The handicaps were overcome in part by the construction of a 
specially designed granular carbon resistance furnace which gave 
sufficiently high temperatures for the melting of the alloys. Fairly 
satisfactory crucibles were made of fused magnesia, which material 
served also as a satisfactory refractory for parts of the furnace. By 
means of these crucibles, melts of about 200 grams could be made. 

The greatest difficulty, however, was encountered in attempting 
to find a protecting tube for the thermo couple which would withstand 
the severe conditions to which it would be exposed. Quartz tubes 
are good for low temperatures, but they cannot be used at the melting 
point of chromium. Porcelain tubes, such as were used by Hindrichs, 
stand slightly higher temperatures than quartz without softening, 
but they break easily and are attacked by chromium. An attempt was 
made to use an alundum tube, but it broke in the first melt. Since it 
was known that the fused magnesia crucibles were little attacked by 
chromium, it was thought that an insulating tube of the same material 
might be satisfactory. Some tubes were moulded, dried, and heated 
to about 1500 degrees C. They became hard and dense, but bent 
during the heating. It apears that in heating the magnesia to 1500 
degrees C. it passes through a semi-fused state at which time sintering 
takes place, but at that same time the tubes bend so badly that they can 
not be used. Some magnesia tubes were moulded in which a solution of 
magnesium chloride was used as the binding material. These tubes, 
after drying at 105 degrees C, were hard and looked promising, but 
when heated they became brittle and crumbled to pieces at 800 to 
900 degrees €. So far, all attempts to prepare satisfactory magnesia 
insulating tubes have failed. Because of so many difficulties and a 
limited amount of time, it was thought best to omit this part of the 
work for the time being, reserving it for later investigation. 

25. Heat Treatment. — As was explained in the introduction it 
has not been considered advisable to attempt much in the way of heat 
treatment of the alloys until the equilibrium diagrams have been more 
thoroughly established. 

Some annealing tests have been carried out and are mentioned 
at the close of this chapter. 

26. Microscopic Examination. 

a. General Discussion. — The metallurgical microscope used in 
the examination of these alloys was a Leitz ' ' Micrometallograph. " 
For the most part apochromatic objectives were used with projection 
eyepieces. Many difficulties were met with in the preparation of the 



36 ILLINOIS ENGINEERING EXPERIMENT STATION 

different alloys for microscopic study. No two alloys had exactly the 
same composition. It is almost equally true that no two of the alloys 
would give the best results by the same methods of polishing, etching, 
staining, and photographing. Thus each specimen became a research 
problem in itself. 

b. Etching Reagents. — A study of the different etching reagents, 
stains, etc., described in the literature, was made in an endeavor to 
find means of identifying the different constituents in the alloys. De- 
scriptions of the two reagents which have been found most effective 
follow : 

Ferric CMoride in HydrocJiloric Acid. — This solution consisted 
of 1 per cent Fed., dissolved in 1:1 HCl. It has been found very 
useful. In some cases it was found necessary to dilute it with one or 
more volumes of water because the etching was too rapid. An 
attempt was made to secure colorations by using a mixture of 25 cc. 
of this solution with 25 cc. of glycerine, 2 grams of resorcin, and 50 
cc. of water, but it did not give any better results. 

Iodine. — Iodine has been used as the tincture and in a solution 
of potassium iodide. These solutions can be used to etch the speci- 
men in some cases, but they have more value in staining the specimen 
after it has been etched with some other reagent. Iodine stains 
copper or the copper rich constituent, giving it a dark appearance ; 
because it has little effect on either chromium or nickel, it has proved 
the best method for identifying the different constituents in those 
alloys. 

Other reagents tried, but with little success, were alkaline 
potassium permanganate, a mixture of picric and nitric acids in amyl 
and ethyl alcohols, picric acid in alcohol, sodium picrate in alcohol, 
and tartaric acid in water. 

Additional information regarding the etching and staining used 
may be obtained by a study of the microphotographs. (Figs. No. 14 
to 65.) 

c. Results. — Some of the results obtained from the microscopic 
examination have been referred to in the previous discussions. In 
general the data given with the microphotographs are sufficient to 
explain them. The composition given is in weight per cent as found 
by analysis, unless otherwise stated. 

CJiromium-Nickel Alloys. — The microscopic examination of the 
alloys of chromium and nickel seems to confirm Voss' conclusions : 

First, that chromium and nickel form a series of solid solutions 
(mixed crystals) in the alloys containing from 100 to 50 per cent 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 37 

of nickel. (See Figs. 24, 34, 43, 51, and 58. Alloys No. 11, 21, 30, 
38, and 45.) 

Second, that chromium and nickel form a eutectic which con- 
tains about 42 per cent of nickel. Guertler does not think that the 
metals form a true eutectic, but calls it a pseudoeutectic. Fig. 63, 
Alloy No. 51, is of an alloy having approximately 42 per cent of 
nickel and which appears to have a eutectic-like structure. Speci- 
men No. 56, Fig. 65, which should contain more chromium, shows 
what appears to be the eutectic structure and an excess of chromium. 
Although alloys containing higher percentages of chromium have 
been prepared, they have not been analyzed and microphotographs of 
them have not been made. The reason for this has been the difficulty 
of cutting proper samples from the extremely hard alloys. 

Copper-Nickel Alloys. — The microphotographs of the alloys of 
copper and nickel agree very well with those obtained by Guertler 
and Tammann, especially for those obtained under similar condi- 
tions ; namely, with slow cooling. The alloys containing more than 
80 per cent of nickel show large polyhedral crystals. Microphoto- 
graphs of the pure metals and their alloys are shown in Figs. 14 
to 24. 

Solubility of CJiromiitm in Copper. — The tendency for chromium 
or a chromium-rich constituent to separate in alloys of chromium 
and copper has already been discussed. This effect may be seen in 
Alloys Nos. 12, 22, and 31 ; Figs. 25, 35, and 44, and in Figs. 2 and 3. 
The chromium or chromium-rich constituent shows either in relief 
or as the light part of the photograph, if the specimen was stained 
with iodine. 

Effect of Nickel on tJie Solubility of Chromium. — The effect of 
the addition of nickel to alloys of chromium, copper, and nickel 
may be studied in the microphotographs of Alloys Nos. 22 to 30, in- 
clusive, Figs. 35 to 43, in which series there is an increase in nickel 
and a decrease in copper. The separation of the chromium or of the 
chromium-rich constituent is apparent in the Alloys Nos. 22 to 26. 
Those containing larger percentages of nickel are more homogene- 
ous. In No. 29, Fig. 42, well-defined polyhedral crystals character- 
istic of a solid solution are shown. Similar effects will be seen if 
other series, such as Nos. 12 to 21, Figs. 25 to 34, and Nos. 31 to 
38, Figs. 44 to 51 are studied. The alloys become practically homo- 
geneous when the amount of nickel is more than three times the amount 
of copper present. 



38 ILLINOIS ENGINEERING EXPERIMENT STATION 

Crystals in Nickel-Ricli Alloys. — It must be remembered that 
the alloys studied were intended to have variations of 10 per cent 
in their different constituents and it is not possible to say at exactly 
what nickel content the binary alloys begin to show well-defined 
polyhedral crystals. From the specimens examined, it is evident 
that in the case of the binary alloys those which contain as much as 
80 per cent of nickel show such crystals. On the other hand, the 
ternary alloys show them if they contain as much as 70 per cent 
of nickel. Of course, the structures which have been obtained in 
these alloys represent what may be expected if the castings are 
slowly cooled, but they do not necessarily show what structure 
would be produced by quenching. 

Annealing Telts. — Small pieces of Alloys Nos. 22 to 38, inclusive, 
were packed in amorphous silica in an iron pipe, 1% by 5 inches 
in dimensions and closed at both ends by caps. The pipe and con- 
tents were placed in an electric furnace and heated at a temperature 
of approximately 900 degrees C. for at least twenty-four hours. The 
specimens were repolished and examined microscopically. From a 
brief examination it seems that there was not any very noticeable 
change in the structure. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 39 




Fig. 14. Alloy No. 1. x 40. 

Cu. 100% 

Etched in 1% FeCls in 1: 1 HCl. 



Fig. 15. Alloy No. 2. x 40. 
90.84% Cu, 9.06% Ni by Weight. 
Etched in 1% FeClj in 1:1 HCl. 




Fig. 16. Alloy No. 3. x 40. 

81.07%c Cu, 18.76% Ni, by Weight. 
Etched in 1% FeCls in 1: 1 HCl. 



Fig. 17. Alloy No. 4. x 40. 

71.16% Cu, 28.46% Ni by Weight. 
Etched in 1% FeCls in 1:1 HCl. 



40 



ILLINOIS ENGINEERING EXPERIMENT STATION 




Fig. 18. Axloy No. 5. x 40. 

61.63% Cu, 38.25% Ni by Weight. 

Etched in 1% FeCls in 1: 1 HCl. 



Fig. 19. Alloy No. 6. x 40. 

48.96% Cu, 49.90% Ni by Weight. 

Etched in 1% FeCls in 1: 1 HCl. 




Fig. 20. Alloy No. 7. x 40. 

69.13%, Cu, 30.59%, Ni. 
Etched in 1% FeClj in 1 : l HCl. 




Fig. 21. Alloy No. 8. x 40. 

41.14% Cu, 58.27%o Ni. 
Etched in 1% FeClg in 1: 1 HCl. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 41 



Fig. 22. Alloy No. 9. x 40. 

20.65% Cu, 79.35% Nl 
Etched in 1% FeCls in 1 : 1 HCl. 













Fig. 23. Alloy No. 10. x 40. 

10.57% Cu, 88.90% Ni. 
Etched in 1% FeClg in 1:1 HCl. 




Fig. 24. Alloy No. 11. x 40. 

99.66% Nl 
Etched in 1% FeCls in 1: 1 HCl. 



Fig. 25. Alloy No. 12. x 40. 

6.08% Cr, 94.20% Cu. 
Etched in 1% FeClg in 1:1 HCl. 



42 



ir.LIXOIS ENGINEERING EXPERIMENT STATION 




FiG. 26. Alloy No. 13. x 40. 

7.8% Cr, 84.4% Cu, 9.3% Ni 
Etched in 1% FeClg m 1: 1 HCl. 



Fig. 27. Alloy No. 14. x 40. 

8.25% Cr, 74.63% Cu, 16.05% Ni. 
Etched in 1% FeClj in 1 : 1 HCl. 




Fig. 28. Allcy No. 15. x 40. 

10.6% Cr, 66.3% Cu, 22.9% Nl 
Etched in 1% FeCL in 1: 1 HCl. 



Fig. 29. Alloy No. 1(5. x 40. 

15.9% Cr, 54.7% Cu, 29.4% Ni. 

Etched in 1% FeCls in 1:1 HCl. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 43 




Fig. 30. Alloy No. 17. x 40. 

10.1% Cr, 42.6% Cu, 48.0% Nl 

Etched in 1% FeCU in 1:1 HCl. 




,•»•• 



*'^'*'^- 










:®i^*^jii 



Fig. 31. Alloy No. 18. x 40. 

13.97% Cr, 32.69% Cu, 54.16% Ni. 
Etched in 1% FeClg in 1:1 HCl. 





















Fig. 32. Alloy No. 19. x 40. 

11.80% Cr, 20.85% Cu, 66.25% Nl 
Etched in 1% FeCls in 1:1 HCl. 



Fig. 33. Alloy No. 20. x 40. 

11.90% Cr, 11.83% Cu, 76.27% Ni, 
Etched in 1% FeCls in 1:1 HCl. 



44 



ILLINOIS ENGINEERING EXPERIMENl STATION 




Fig. 34. Alloy No. 21. x 40. 

19.37% Cr, 78.99% Ni. 
Etched in 1% FeClg in 1 : 1 HCl. 



Fig. 35. Alloy No. 22. x 40. 
13.15% Cr, 87.93% Cu. 
Not Etched. Stained in I in KI. 




Fig. 36. Alloy No. 23. x 40. 
10.56% Cr, 80.58% Cu, 9.38%, Ni. 
Etched Lightly in 1% FeClj in 1: 
HCl. 



Fig. 37. Alloy No. 24. x 40. 

14.56% Cr, 56.30%, Cu, 29.24%, Nl 

Etched and then Stained in I in KI. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 45 




Fig. 38. Alloy No. 25. x 40. 

13.62% Cr, 66.92% Cu, 19.20% Ni. 

Etched and then Stained in I in KI. 



Fig. 39. Alloyed No. 26. x 40. 
19.30% Ce, 44.08% Cu, 36.34% Nl 
Not Etched, but Stained in I in KI. 




Fig. 40. Alloy No. 27. x 40. 

15.99% Cr, 36.70% Cu, 47.31% Ni. 

Stained in I in alcohol. 






^v fii 






Fig. 41. Alloy No. 28. x 40. 

19.86% Cr, 22.20% Cu, 57.36% Ni, 

Stained in I in alcohol. 



46 



ILLINOIS ENGINEERING EXPERIMENT STATION 




Fig. 42. Alloy No. 29. x 40. 

19.64% Cr, 10.88% Cu, 68.62% Ni. 
Etched in 1% FeCl^ in 1:1 HCl. 



Fig. 43. Alloy No. 30. x 40. 

21.52% Cr, 76.95% Ni. 
Etched in 1% FeClj in 1: 1 HCL 




Fig. 44. Alloy No. 31. x 40 

9.89% Cr, 89.82% Cu. 
Not Etched. Relief Polishing. 







Fig. 45. Alloy No. 32. x 40. 

17.66% Cr, 73.63% Cu, 8.55%, Ni. 
Not Etched. Relief Polishing. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 47 




Fig. 46. Alloy No. 33. x 40. 

22.00% Cr, 59.62% Cu, 19.48% Ni. 

Etched in I in KI. 



Fig. 47. Alloy No. 34. x 40. 

25.10% Cr, 45.70% Cu, 29.52% Nl 
Etched, then Stained in I in KI. 




Fig. 48. Alloy No. 35. x 40. 

29.46%, Cr, 33.76% Cu, 36.78% Ni. 
Etched, then Stained in I in KI. 









i^m-'^ 






Fig. 49. Alloy No. 36. x 40. 

28.10% Cr, 22.58% Cu, 48.42% Nl 
Etched, then Stained in I in KI. 



48 



ILLINOIS ENGINEERING EXPERIMENT STATION 







% 






X 40. 



Fig. 50. Alloy No. 37. 
29.70% Cr, 10.90% Cu, 58.12% Ni. 
Etched in 1% FeClg in 1: 1 HCl. 






>^ 



Fig. 51. Alloy No. 38. x 40. 

28.44% Cr, 71.56% Ni. 
Etched in 1% FeCU in 1: 1 HCl. 




Fig. 52. Alloy No. 39. x 40. 

Approx. 35.29% Cr, 64.71% Cu. 



Fig. 53. Alloy No. 40. x 40. 

19.93%Cr, 70.57% Cu, 8.99% Ni. 
Not Etched. Eelief Polishing. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 49 




Fig. 54. Alloy No., 41. x 40. 

31.63% Cr, 54.16% Cu, 14.21% Ni. 

Stained in I in alcohol. 



Fig. 55. Alloy No. 42. x 40. 

38.16% Cr, 33.60% Cu, 26.78% Nl 

Etched, then Stained in I in 

Alcohol. 




Fig. 56. Alloy No. 43. x 40. 

41.32%, Cr, 22.68%, Cu, 34.60% Nl 

Etched, then Stained ix I in 

Alcohol. 



Fig. 57. Alloy Xo. 44. x 40. 

43.30% Cr, 11.02%, Cu, 46.46%, Ni. 

Etched, then Stained in I in 

Alcohol. 



50 



ILLINOIS ENGINEERING EXPERIMENT STATION 




Fig. 58. Alloy No. 45. x 40. 

44.93% Cr, 56.55% Nl 

Etched in Aqua Regl-^. 



Fig. 59. Alloy No. 48. x 60. 

54.92% Cr, 28.42% Cu, 17.12% Nl 

Stained in I in Alcohol. 




Fig. 60. Alloy No. 49. x 40. 

47.54% Cr, 24.12% Cu, 26.28% Ni. 

Polished. Not Etched. 



Fig. 61. Alloy No. 49. x 40. 

47.54% Cr, 24.12% Cu, 26.28% Nl 

Stained in I in KI. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 51 




Fig. 62. Alloy Xo. 50. x 40. 

Approx. 46.6% Cr, 11.4% Cu, 42.0% 

Ni. 

Stained in I in Alcohol. 



Fig. 63. Alloy Xo. 51. x 40. 

57.40% Cr, 41.66% Nl 

Etched in Aqua Eegia. 









Jl^. 






i%\ 





Fig. 64. Alloy Xo. 55. x 40. 

Approx. 56.6%, Cr, 11.5% Cu, 31.9%, 

Xi. 

Etched in Aqua Eegta. 




Fig. 65. Alloy Xo. 56. x 40. 

Approx. 57% Cr, 43% Ni. 
Etched in 1% FeClj in 1:1 HCl. 
THEN Stained in I in Alcohol. 



52 ILLINOIS ENGINEERING EXPERIMENT STATION 

APPENDIX 

Historical Review 

In this review it is intended to give only the more important 
results of previous investigations and references to the original 
publications. 

1. Copper-Nickel Alloys. — Christofle and Bouilhet* prepared 
alloys containing 50 per cent of copper and 50 per cent of nickel, 
and 85 per cent of copper and 15 per cent of nickel, and observed 
some of their properties. 

In 1896 H. Gautierf made a more extensive study of these 
alloys. He determined their freezing points and concluded that they 
formed a definite chemical compound having the formula CuNi which 
melted at 1340 degrees C. The original paper was presented by H. 
Moissan. 

Heycoek and Neville^ in their work on the "Complete Freezing- 
point Curves of Binary Alloys containing Silver or Copper together 
with Another Metal" tried the effect of the addition of small 
amounts of nickel upon the freezing point of copper and found that 
the freezing point was raised from 1080 to 1110 degrees C. by the 
addition of 4.5 per cent of nickel. 

Kurnakoff and SchemtschnyTJ prepared alloys from electrolytic 
copper and nickel, determined their freezing points, plotted the 
freezing-point curve, studied the structure of the different speci- 
mens, and pointed out certain similarities to the alloys of iron- 
copper, cobalt-copper, and copper-nickel. They took 1484 degrees 
C. as the melting point of nickel which is now known to be too high. 

Guertler and Tammann§ in their investigation of the alloys of 
copper and nickel showed that there was no break in either the 
liquidus or solidus curves. This showed that these alloys do not 
form a definite chemical compound as had been claimed by H. 
Gautier. They made also both magnetic and microscopic examina- 
tions and showed the effect of heat on the magnetic properties as 
well as the effect of the rate of cooling on the grain and crystal 
size. 



*Christofle and Bouilhet, Bui. Soc. Chem., Vol. 26, p. 419, 1876. 
Compt. rend., Vol. 83, p. 29, 1876. 

tH. Gautier, Compt. rend., Vol. 123, p. 172, 1896. 

JHeycock and Neville, Philos. Trans., 189A, p. 25, 1897. 

IlKurnakoff and Schemtschny, Z. anorg. Chem., Vol. 54, p. 149, 1907 

§Guertler and Tammann, Z. anorg. Chem., Vol. 52, p. 25, 1907. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 53 

The following year (1908) Victor E. Tafel* published the results 
of his studies of the constitution of the binary system copper- 
nickel. His work seems to be the best that has been published. For 
convenience his results are shown diagrammatically in Fig. 66. He 
obtained higher values for both the liquidus and the solidus curves 
than did Guertler and Tammann, but that may be attributed to the 
fact that they used nickel which contained a considerable amount of 
impurities (0.47 per cent Fe, 1.86 per cent Co.) which would lower 
the freezing points. 

E. Vigourouxf, using pure metals especially free from cobalt, 
prepared a series of copper-nickel alloys, but he was unable to detect 
any indication of definite chemical compounds by chemical investiga- 

IST 
tion or by a study of the electromotive forces in the cells Ni — — -, 

NiSOi — OuNi alloy and Cu , NiSOi — CnXi alloy. His results 

by this method agree with those obtained by the cooling-curve 
method. 



1500 








































Jj.' 


1400 


































^^ 


r^ 


^ 


?^ 






























"^ 




^ 








1300 








u 


qu/'afi 


J5 








^, 


> 




-y 


A 


^' 


























dolic 


iu5' 




_^ 


A 


Y 
















V5 














^ 


J 


v\ 




















%l^00 

% 


5chmelze 
Nr 


Geh. ber 
Gew. - Proz. 


Beginn | Ende 
derKri5follisc 
"C. 1 X. 


Infervoll ~ 
)fion 

"c. - 






,^ 


^ 


J 


— < 




^ 


"^ 


t 


-^ 


^ 
















Cu 


Nl 


%II00, 


— 


100.0 


— 


1064 


— 


"Cu 


















/ 


99.5 


05 


1086 


— 


— 


I 


90.0 


10.0 


1149 


III! 


36 _ 






















3 


60.0 


20.0 


1194 


1129 


65 


1000 


4 


70.0 


30.0 


1239 


1157 


82 _ 




















5 


60.0 


40.0 


1265 


1190 


95 






6 


50.0 


50.0 


1314 


1233 


81 _ 




















7 


40.0 


60.0 


1349 


1282 


67 


900 


6 


30.0 


70.0 


1360 


1323 


57 _ 




















9 


20.0 


60.0 


1411 


1373 


36 




10 


10.0 


90.0 


1436 \ 1405 


33 _ 


















\ 1 




0.0 


100.0 


1451 










1 1 1 1 1 i 1 1 1 1 1 1 



10 do JO 40 50 60 

Percent Ni by Weight 



70 



60 



90 



100 



Fig. 66. Copper-Nickel Equilibrium Diagram After Tafel. 



♦Victor E. Tafel, Metalliirgie, Vol. 5, p. 348, 1908. 
tE. VigouroTxx, Compt. rend., Vol. 159, p. 1378, 1909. 



54 ILLINOIS ENGINEERING EXPERIMENT STATION 

David H. Browne* secured U. S. patent 934,278 (Sept. 14, 1910) 
for the manufacture of nickel and copper-nickel alloys by electric- 
ally fusing compounds of the metals as sulfide matte with lime (CaO), 
forming calcium sulfide (CaS), sulfur dioxide (S02), and an alloy 
of the metals. 

2. CJiromium-Copper Alloys. — H. Moissanf prepared an alloy 
of chromium and copper which contained about 0.5 per cent of chrom- 
ium. It was more resistant to humid air than was copper and took a 
beautiful polish. 

H. GoldschmidtJ has described an alloy of chromium and cop- 
per containing 10 per cent of chromium and having the color of 
copper, but being harder. The Goldschmidt Thermit CompanyTf, 90 
"West Street, New York, now offers for sale an alloy of chromium- 
/ copper containing 10 per cent of chromium. The alloy is made by 
the aluminothermic method. This alloy is discussed more fully in 
Chapter II. 

Hamilton and Smith§ heated chromium oxide and metallic 
copper in a carbon crucible and in the presence of carbon, by which 
process they obtained an alloy of gray-red color and of a hardness 
which placed it next to the alloys containing tungsten and 
molybdenum. The alloy gave the analysis: 88.18 per cent Cu, 3.22 
per cent Cr, 1.35 per cent Fe, 2.38 per cent C, and 4.13 per cent 
gangue. The specific gravity was 8.3. 

Binet de Jassonnix** stated that chromium dissolved in copper 
to the extent of about 1.6 per cent, but that on cooling, the chro- 
mium separated in a very finely divided condition. 

G. Hindrichsft made a more extensive study of the alloys of 
chromium and copper. He decided that the freezing point of cop- 
per was lowered about eight degrees by the addition of 0.5 per 
cent of chromium and that the maximum solubility of chromium in 
copper was 0.5 per cent. He, likewise, found that the freezing 
point of chromium was lowered from 1550 to about 1470 degrees C. 
by the addition of 5 per cent of copper and considered that the 
maximum solubility of copper in chromium was not over 5 per 
cent. From his researches it seems that there are two eutectic 



♦David H. Browne, C. A., Vol. 4, p. 41, 1910. 

tH. Moissan, Compt. rend., Vol. 119, p. 185, 1894. 
H. Moissan, Compt. rend., Vol. 122, p. 1302, 1896. 

JH. Goldschmidt, Liebigs Ann., Vol. 301, p. 25, 1898. 

HThermit Carbon-Free Metals, Pamphlet No. 20, 2nd ed., p. 23. 

§Hamilton and Smith, Jour. Am. Chem. Soc, Vol. 23, p. 151, 1901. 

**Binet de Jassonix, Compt. rend., Vol. 144, p. 915, 1907. 

ttG. Hindrichs, Z. anorg. Chem., Vol. 59, p. 414, 1908. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKEL 55 

points in the chromium-copper freezing point curve. His chro- 
mium-copper diagram has been reproduced in Fig. 67. He pointed 
out some of the difficulties in working with chromium or chromium- 
copper alloys. Chromium remains viscous after melting, attacks 
the crucibles, insulating tubes, etc., and has a strong tendency to 
oxidize. He was not able to get chromium and copper to separate 
into two well-defined layers. 

From the foregoing paragraphs it may be seen that the different 
investigators have placed the solubility of chromium in copper at 
0.5, 1.6, 3.22, and 10 per cents. 



1600 


1 

.5 Cr 


d 
































1500 


\ 
\ 
\ 


/ 














1 






















f^ 


' 






-— — 1 











_-_L— 
















— ■^•m. 


«J-W»w 




E 
— 1 


1400 




jrvj 





1 i 


t=^ 












— 1 




























































K^ 1500 

t 

1 


































































































































































1 

1100 








( 


) 
































F 














( 










) 


< 


^ 


I 


1 1 


< 


1 


A 


1000 




1 


\' 






■ 1 




I 


^ 






< 


\ 


— 1 






1 






55 

















































































10 iO 30 40 50 60 

Perce nf Cu by Weigh f 



70 



60 



90 



100 



Fig. 67. Copper-Chromium Equilibrium Diagram After Hindrichs. 



3. Chromium-Nickel Alloys. — G. Voss* has investigated the 
alloys of chromium and nickel. His chromium-nickel diagram has 
been reproduced in Fig. 68. At the time he published his paper 
he stated that he was unable to find any published literature on the 
subject and at the present time he seems to be the only one who 
has published his researches. However, there have been extensive 
researches in the development of such alloys as ''Nichrome", but 
these have been conducted in commercial laboratories and the re- 



*G. Voss, Z. anorg. Chem., Vol. 57, p. 34, 1908. 



56 



ILLINOIS ENGINEERING EXPERIMENT STATION 



suits have not been published. Voss showed that the system con- 
sists of two series of solid solutions with a minimum freezing point 
of about 42 per cent of nickel. From a microscopic examination he 
concluded that the point represented a true eutectic, although he 
was not able to demonstrate the presence of a eutectic structure 
on either side of this point. He assumed the presence of a solution 
gap (Mischungsliicke). On the other hand Guertler* concluded 
that the structure represented a condition of unstable equilibrium, 
which he termed a psuedoeutectic produced by the extreme viscosity 
of the chromium. 



^3 

I 
I 
I 



1600 
1500 

1400 

1300 



300 



dOO 



100 



A 








































^> 


>. 








^ 


!i. 
































V 








\ 


























A 








V 


V 






\ 
















--^ 


' — 


( 


)^^ 


(^ 












^^^ 


X 


N 


V 














^ 


^ 


^ 










Cr ncn. 
f^ixed crysfab. 






\^ 


%A 


Vu 


( 


)__^ — ■ 


-^ 




Hirich. 

Mixed crysfa/s, 
non-mognef/ 










non-mognefic. 

1 1 






i^r 


r^ 












r 
> 


































































































































































1 








































/ 








































^r^ 

1 
1 








































1 
1 
1 








































1 



10 



20 



30 



70 



60 



40 50 60 

Percent Ni by Weighr 

Fig. 68. Nickel-Chromium Equilibrium Diagram After Voss 



90 100 



To summarize, the binary alloys belong to three different 
classes: copper-nickel representing those which have continuous 
freezing-point curves, chromium-nickel representing those which 
have two series of solid solutions and a minimum freezing point, 
and chromium-copper those which have two eutectic points. The 
freezing-point curves for copper-nickel and for chromium-nickel 
seem to be pretty well established, but the exact location of a large 
part of the freezing-point curve for chromium-copper is unknown. 



*Guertler, Metallographie, Vol. 1. Part I, p. 209, 1912. 



A STUDY OF THE ALLOYS OF CHROMIUM, COPPER, AND NICKETi -U 

4. Ternary Alloys. — The ternary alloys of chromium-copper- 
iiickel have not been described, so far as is known to the writers, 
but four ternary systems which are somewhat closely related have 
been reported: copper-nickel-zinc by Victor E. Tafel,* copper- 
iron-nickel by R. Vogeljt copper-manganese-nickel by N. Parravano,J 
and cobalt-copper-nickel by Wahlert.^ 



♦Victor E. Tafel, Metallurgie, Vol. 5, p. 413, 1908. 
tR. Vogel, Z. anorg. Chem., Vol. 67, p. 1, 1910. 
$N. Parravano, Inter. Z. Metallographie, Vol. 4, p. 171, 1913. 

^jWahlert, Oester. Z. Berg. Hiittenw.,' Vol. 62, pp. 341-6, 357-61, 374-8, 392-5, and 406- 
10, 1914. C.A., Vol. 8, p. 3549, 1914. 



58 ILLINOIS ENGINEERING EXPERIMENT STATION 



ACKNOWLEDGMENTS 

In this work valuable assistance has been received from a large 
number of persons connected with the University of Illinois and the 
writer wishes to express his gratitude to those persons. 

Professor D. F. McFarland has had charge of the entire investi- 
gation and has given much encouragement and assistance. Professor 
S. W. Parr has given many helpful suggestions. Professor II. F. 
Moore of the Department of Theoretical and Applied Mechanics 
directed the mechanical tests and criticised that part of the thesis. 
Mr. S. M. Hull made the copper and nickel determinations. Others 
to whom the writer is under obligations include Drs. Beal, Broderson 
and Maclnnes, Messrs. Ford, "Westhafer, McClelland, Rowland, Lee, 
and Brown and Miss Scott. The writer is also under obligations to 
the University of Illinois for a Fellowship in Chemistry during tlie 
two years that this investigation has been in progress. 



VITA 

The writer received his elementary education in the rural schools 
of Arkansas, Texas, and Oklahoma Territory. He received his sec- 
ondary education in the Preparatory Department of the University 
of Oklahoma at Norman, Oklahoma, in the Agricultural and Me- 
chanical College at Stillwater, Oklahoma, and in the Central State 
Normal School at Edmond, Oklahoma. He entered the University of 
Oklahoma in 1906 and graduated from that institution with the de- 
gree of B.A., 1910, and M.A., 1911, with majors in chemistry. He 
was instructor in Chemistry and Clerk of the Chemical Laboratory 
of the University of Oklahoma in 1910-1911 and in the summer ses- 
sions of 1910 and 1911. He became Food Analyst for the Kansas 
State Board of Health in 1911 with the rank of Assistant Professor 
at the University of Kansas. In 1913 he was placed in charge of the 
Food Laboratory. In September, 1913, he came to the University of 
Illinois as a Fellow in Chemistry and has remained in that position 
to the present time. His publications include : 

''Note on the Standard Vanillin Solution for the Colorometric 
Method for the Determination of Vanillin in Flavoring Extracts", 
J. Ind. Eng. Chem. 5, (1913) p. 619. 

Food Analysis Reports. Bulletin of the Kansas State Board of 
Health, 7, (1913) pp. 54-57, 70-74, 136-138, 150-153 and 167-173. 



2-1917 



il«,S,L,,S,f CONGRESS 

^ mmmmii 

019 423 354 



